An enzyme that catalyzes the conversion of carbamoyl phosphate and L-aspartate to yield orthophosphate and N-carbamoyl-L-aspartate. (From Enzyme Nomenclature, 1992) EC 2.1.3.2.
A urea cycle enzyme that catalyzes the formation of orthophosphate and L-citrulline (CITRULLINE) from CARBAMOYL PHOSPHATE and L-ornithine (ORNITHINE). Deficiency of this enzyme may be transmitted as an X-linked trait. EC 2.1.3.3.
An enzyme that, in the course of pyrimidine biosynthesis, catalyzes ring closure by removal of water from N-carbamoylaspartate to yield dihydro-orotic acid. EC 3.5.2.3.
An enzyme that catalyzes the formation of carbamoyl phosphate from ATP, carbon dioxide, and glutamine. This enzyme is important in the de novo biosynthesis of pyrimidines. EC 6.3.5.5.
The monoanhydride of carbamic acid with PHOSPHORIC ACID. It is an important intermediate metabolite and is synthesized enzymatically by CARBAMYL-PHOSPHATE SYNTHASE (AMMONIA) and CARBAMOYL-PHOSPHATE SYNTHASE (GLUTAMINE-HYDROLYZING).
Cytidine 5'-(tetrahydrogen triphosphate). A cytosine nucleotide containing three phosphate groups esterified to the sugar moiety.
A simple organophosphorus compound that inhibits DNA polymerase, especially in viruses and is used as an antiviral agent.
A genus of gram-negative, curved or straight rod-shaped bacteria, in the family ALTEROMONADACEAE. They are chemo-organotrophic, halophilic, and associated with cold marine habitats.
An enzyme that in the course of pyrimidine biosynthesis, catalyzes the oxidation of dihydro-orotic acid to orotic acid utilizing oxygen as the electron acceptor. This enzyme is a flavoprotein which contains both FLAVIN-ADENINE DINUCLEOTIDE and FLAVIN MONONUCLEOTIDE as well as iron-sulfur centers. EC 1.3.3.1.
One of the non-essential amino acids commonly occurring in the L-form. It is found in animals and plants, especially in sugar cane and sugar beets. It may be a neurotransmitter.
The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.
The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
A group of enzymes that catalyze the transfer of carboxyl- or carbamoyl- groups. EC 2.1.3.
An inherited urea cycle disorder associated with deficiency of the enzyme ORNITHINE CARBAMOYLTRANSFERASE, transmitted as an X-linked trait and featuring elevations of amino acids and ammonia in the serum. Clinical features, which are more prominent in males, include seizures, behavioral alterations, episodic vomiting, lethargy, and coma. (Menkes, Textbook of Child Neurology, 5th ed, pp49-50)
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
An amino acid produced in the urea cycle by the splitting off of urea from arginine.
Enzymes of the transferase class that catalyze the conversion of L-aspartate and 2-ketoglutarate to oxaloacetate and L-glutamate. EC 2.6.1.1.
Citrulline is an α-amino acid, primarily produced in the urea cycle in the liver and found in some dietary proteins, which functions as a vital intermediator in the nitrogen metabolism and vasodilation, and can be supplemented for potential health benefits in improving blood flow, reducing fatigue, and enhancing exercise performance.
A class of enzymes that transfers phosphate groups and has a carboxyl group as an acceptor. EC 2.7.2.
Orotic acid, also known as pyrophosphoric acid dihydrate, is a organic compound that plays a role in the biosynthesis of pyrimidines, and elevated levels of orotic acid in urine can indicate certain genetic disorders or liver dysfunction.
A pyridoxal phosphate enzyme that catalyzes the formation of glutamate gamma-semialdehyde and an L-amino acid from L-ornithine and a 2-keto-acid. EC 2.6.1.13.
An enzyme that catalyzes the formation of carbamoyl phosphate from ATP, carbon dioxide, and ammonia. This enzyme is specific for arginine biosynthesis or the urea cycle. Absence or lack of this enzyme may cause CARBAMOYL-PHOSPHATE SYNTHASE I DEFICIENCY DISEASE. EC 6.3.4.16.
Any member of the class of enzymes that catalyze the cleavage of the substrate and the addition of water to the resulting molecules, e.g., ESTERASES, glycosidases (GLYCOSIDE HYDROLASES), lipases, NUCLEOTIDASES, peptidases (PEPTIDE HYDROLASES), and phosphatases (PHOSPHORIC MONOESTER HYDROLASES). EC 3.
An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease ARGININOSUCCINIC ACIDURIA in man. EC 4.3.2.1.
An essential amino acid that is physiologically active in the L-form.
A ureahydrolase that catalyzes the hydrolysis of arginine or canavanine to yield L-ornithine (ORNITHINE) and urea. Deficiency of this enzyme causes HYPERARGININEMIA. EC 3.5.3.1.
The sodium salt of BENZOIC ACID. It is used as an antifungal preservative in pharmaceutical preparations and foods. It may also be used as a test for liver function.
Inorganic or organic salts and esters of arsenic acid.
Transferases are enzymes transferring a group, for example, the methyl group or a glycosyl group, from one compound (generally regarded as donor) to another compound (generally regarded as acceptor). The classification is based on the scheme "donor:acceptor group transferase". (Enzyme Nomenclature, 1992) EC 2.
The rate dynamics in chemical or physical systems.
A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
A species of strictly anaerobic, hyperthermophilic archaea which lives in geothermally-heated marine sediments. It exhibits heterotropic growth by fermentation or sulfur respiration.
An enzyme of the urea cycle that catalyzes the formation of argininosuccinic acid from citrulline and aspartic acid in the presence of ATP. Absence or deficiency of this enzyme causes the metabolic disease CITRULLINEMIA in humans. EC 6.3.4.5.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

Assessment of the allosteric mechanism of aspartate transcarbamoylase based on the crystalline structure of the unregulated catalytic subunit. (1/437)

The lack of knowledge of the three-dimensional structure of the trimeric, catalytic (C) subunit of aspartate transcarbamoylase (ATCase) has impeded understanding of the allosteric regulation of this enzyme and left unresolved the mechanism by which the active, unregulated C trimers are inactivated on incorporation into the unliganded (taut or T state) holoenzyme. Surprisingly, the isolated C trimer, based on the 1.9-A crystal structure reported here, resembles more closely the trimers in the T state enzyme than in the holoenzyme:bisubstrate-analog complex, which has been considered as the active, relaxed (R) state enzyme. Unlike the C trimer in either the T state or bisubstrate-analog-bound holoenzyme, the isolated C trimer lacks 3-fold symmetry, and the active sites are partially disordered. The flexibility of the C trimer, contrasted to the highly constrained T state ATCase, suggests that regulation of the holoenzyme involves modulating the potential for conformational changes essential for catalysis. Large differences in structure between the active C trimer and the holoenzyme:bisubstrate-analog complex call into question the view that this complex represents the activated R state of ATCase.  (+info)

Simulations of the T <--> R conformational transition in aspartate transcarbamylase. (2/437)

Aspartate transcarbamylase (ATCase) from Escherichia coli is one of the best known allosteric enzymes. In spite of numerous experiments performed by biochemists, no consensus model for the cooperative transition between the tensed (T) and the relaxed (R) forms exists. It is hypothesized, however, that changes in the quaternary structure play a key role in the allosteric properties of oligomeric proteins such as ATCase. Previous normal mode calculations of the two states of ATCase illustrated the type of motions that could be important in initiating the transition. In this work four pathways for the transition were calculated using the targeted molecular dynamics (TMD) method without constraint on the symmetry of the system. The most important quaternary structure changes are the relative rotation and translation of the catalytic trimers and the rotations of the regulatory dimers. The simulations show that these quaternary changes start immediately and finish when about 70% of the transition is completed whereas there are tertiary changes throughout the transition. In agreement with the work of Lipscomb et al., it was found that the relative translation between the catalytic trimers appears to play a central role in allowing the transition to occur. In all the simulations differences are observed in the opening and closing behaviours of the domains in the catalytic and regulatory chains that could provide a structural interpretation for the results of certain site-directed mutagenesis experiments. Overall the motions of the subunits are concerted even though the constraint imposed on the TMD method does not explicitly require that this be so.  (+info)

Micronuclei formation with chromosome breaks and gene amplification caused by Vpr, an accessory gene of human immunodeficiency virus. (3/437)

Vpr, an accessory gene of human immunodeficiency virus, induces cell cycle abnormality by accumulating cells at the G2-M phase. We reported recently that Vpr caused both micronuclei formation and aneuploidy. Here, we show that Vpr also induced chromosome breaks and gene amplification. Expression of Vpr induced more than 10-fold increase of colonies resistant to N-(phosphonacetyl)-L-aspartate, an inhibitor of pyrimidine de novo synthesis. Fluorescence in situ hybridization analysis detected that 4 of 10 N-(phosphonacetyl)-L-aspartate resistant clones studied had intrachromosomal amplification of carbamyl-phosphate synthetase/aspartate transcarbamoylase/dihydroorotase gene. Another single clone had dicentrics. Data suggested that the Vpr-induced chromosome breaks leading to gene amplification, followed by bridge-breakage-fusion cycle, were one of the possible mechanisms of Vpr-induced genomic instability.  (+info)

The 80s loop of the catalytic chain of Escherichia coli aspartate transcarbamoylase is critical for catalysis and homotropic cooperativity. (4/437)

The X-ray structure of the Escherichia coli aspartate transcarbamoylase with the bisubstrate analog phosphonacetyl-L-aspartate (PALA) bound shows that PALA interacts with Lys84 from an adjacent catalytic chain. To probe the function of Lys84, site-specific mutagenesis was used to convert Lys84 to alanine, threonine, and asparagine. The K84N and K84T enzymes exhibited 0.08 and 0.29% of the activity of the wild-type enzyme, respectively. However, the K84A enzyme retained 12% of the activity of the wild-type enzyme. For each of these enzymes, the affinity for aspartate was reduced 5- to 10-fold, and the affinity for carbamoyl phosphate was reduced 10- to 30-fold. The enzymes K84N and K84T exhibited no appreciable cooperativity, whereas the K84A enzyme exhibited a Hill coefficient of 1.8. The residual cooperativity and enhanced activity of the K84A enzyme suggest that in this enzyme another mechanism functions to restore catalytic activity. Modeling studies as well as molecular dynamics simulations suggest that in the case of only the K84A enzyme, the lysine residue at position 83 can reorient into the active site and complement for the loss of Lys84. This hypothesis was tested by the creation and analysis of the K83A enzyme and a double mutant enzyme (DM) that has both Lys83 and Lys84 replaced by alanine. The DM enzyme has no cooperativity and exhibited 0.18% of wild-type activity, while the K83A enzyme exhibited 61% of wild-type activity. These data suggest that Lys84 is not only catalytically important, but is also essential for binding both substrates and creation of the high-activity, high-affinity active site. Since low-angle X-ray scattering demonstrated that the mutant enzymes can be converted to the R-structural state, the loss of cooperativity must be related to the inability of these mutant enzymes to form the high-activity, high-affinity active site characteristic of the R-functional state of the enzyme.  (+info)

Half of Saccharomyces cerevisiae carbamoyl phosphate synthetase produces and channels carbamoyl phosphate to the fused aspartate transcarbamoylase domain. (5/437)

The first two steps of the de novo pyrimidine biosynthetic pathway in Saccharomyces cerevisiae are catalyzed by a 240-kDa bifunctional protein encoded by the ura2 locus. Although the constituent enzymes, carbamoyl phosphate synthetase (CPSase) and aspartate transcarbamoylase (ATCase) function independently, there are interdomain interactions uniquely associated with the multifunctional protein. Both CPSase and ATCase are feedback inhibited by UTP. Moreover, the intermediate carbamoyl phosphate is channeled from the CPSase domain where it is synthesized to the ATCase domain where it is used in the synthesis of carbamoyl aspartate. To better understand these processes, a recombinant plasmid was constructed that encoded a protein lacking the amidotransferase domain and the amino half of the CPSase domain, a 100-kDa chain segment. The truncated complex consisted of the carboxyl half of the CPSase domain fused to the ATCase domain via the pDHO domain, an inactive dihydroorotase homologue that bridges the two functional domains in the native molecule. Not only was the "half CPSase" catalytically active, but it was regulated by UTP to the same extent as the parent molecule. In contrast, the ATCase domain was no longer sensitive to the nucleotide, suggesting that the two catalytic activities are controlled by distinct mechanisms. Most remarkably, isotope dilution and transient time measurements showed that the truncated complex channels carbamoyl phosphate. The overall CPSase-ATCase reaction is much less sensitive than the parent molecule to the ATCase bisubstrate analogue, N-phosphonacetyl-L-aspartate (PALA), providing evidence that the endogenously produced carbamoyl phosphate is sequestered and channeled to the ATCase active site.  (+info)

Aspartate carbamoyltransferase from the thermoacidophilic archaeon Sulfolobus acidocaldarius. Cloning, sequence analysis, enzyme purification and characterization. (6/437)

The genes coding for aspartate carbamoyltransferase (ATCase) in the extremely thermophilic archaeon Sulfolobus acidocaldarius have been cloned by complementation of a pyrBI deletion mutant of Escherichia coli. Sequencing revealed the existence of an enterobacterial-like pyrBI operon encoding a catalytic chain of 299 amino acids (34 kDa) and a regulatory chain of 170 amino acids (17.9 kDa). The deduced amino acid sequences of the pyrB and pyrI genes showed 27.6-50% identity with archaeal and enterobacterial ATCases. The recombinant S. acidocaldarius ATCase was purified to homogeneity, allowing the first detailed studies of an ATCase isolated from a thermophilic organism. The recombinant enzyme displayed the same properties as the ATCase synthesized in the native host. It is highly thermostable and exhibits Michaelian saturation kinetics for carbamoylphosphate (CP) and positive homotropic cooperative interactions for the binding of L-aspartate. Moreover, it is activated by nucleoside triphosphates whereas the catalytic subunits alone are inhibited. The holoenzyme purified from recombinant E. coli cells or present in crude extract of the native host have an Mr of 340 000 as estimated by gel filtration, suggesting that it has a quaternary structure similar to that of E. coli ATCase. Only monomers could be found in extracts of recombinant E. coli or Saccharomyces cerevisiae cells expressing the pyrB gene alone. In the presence of CP these monomers assembled into trimers. The stability of S. acidocaldarius ATCase and the allosteric properties of the enzyme are discussed in function of a modeling study.  (+info)

Functional linkage between the glutaminase and synthetase domains of carbamoyl-phosphate synthetase. Role of serine 44 in carbamoyl-phosphate synthetase-aspartate carbamoyltransferase-dihydroorotase (cad). (7/437)

Mammalian carbamoyl-phosphate synthetase is part of carbamoyl-phosphate synthetase-aspartate carbamoyltransferase-dihydroorotase (CAD), a multifunctional protein that also catalyzes the second and third steps of pyrimidine biosynthesis. Carbamoyl phosphate synthesis requires the concerted action of the glutaminase (GLN) and carbamoyl-phosphate synthetase domains of CAD. There is a functional linkage between these domains such that glutamine hydrolysis on the GLN domain does not occur at a significant rate unless ATP and HCO(3)(-), the other substrates needed for carbamoyl phosphate synthesis, bind to the synthetase domain. The GLN domain consists of catalytic and attenuation subdomains. In the separately cloned GLN domain, the catalytic subdomain is down-regulated by interactions with the attenuation domain, a process thought to be part of the functional linkage. Replacement of Ser(44) in the GLN attenuation domain with alanine increases the k(cat)/K(m) for glutamine hydrolysis 680-fold. The formation of a functional hybrid between the mammalian Ser(44) GLN domain and the Escherichia coli carbamoyl-phosphate synthetase large subunit had little effect on glutamine hydrolysis. In contrast, ATP and HCO(3)(-) did not stimulate the glutaminase activity, indicating that the interdomain linkage had been disrupted. In accord with this interpretation, the rate of glutamine hydrolysis and carbamoyl phosphate synthesis were no longer coordinated. Approximately 3 times more glutamine was hydrolyzed by the Ser(44) --> Ala mutant than that needed for carbamoyl phosphate synthesis. Ser(44), the only attenuation subdomain residue that extends into the GLN active site, appears to be an integral component of the regulatory circuit that phases glutamine hydrolysis and carbamoyl phosphate synthesis.  (+info)

Substitutions in the aspartate transcarbamoylase domain of hamster CAD disrupt oligomeric structure. (8/437)

Aspartate transcarbamoylase (ATCase; EC 2.1.3.2) is one of three enzymatic domains of CAD, a protein whose native structure is usually a hexamer of identical subunits. Alanine substitutions for the ATCase residues Asp-90 and Arg-269 were generated in a bicistronic vector that encodes a 6-histidine-tagged hamster CAD. Stably transfected mammalian cells expressing high levels of CAD were easily isolated and CAD purification was simplified over previous procedures. The substitutions reduce the ATCase V(max) of the altered CADs by 11-fold and 46-fold, respectively, as well as affect the enzyme's affinity for aspartate. At 25 mM Mg(2+), these substitutions cause the oligomeric CAD to dissociate into monomers. Under the same dissociating conditions, incubating the altered CAD with the ATCase substrate carbamoyl phosphate or the bisubstrate analogue N-phosphonacetyl-L-aspartate unexpectedly leads to the reformation of hexamers. Incubation with the other ATCase substrate, aspartate, has no effect. These results demonstrate that the ATCase domain is central to hexamer formation in CAD and suggest that the ATCase reaction mechanism is ordered in the same manner as the Escherichia coli ATCase. Finally, the data indicate that the binding of carbamoyl phosphate induces conformational changes that enhance the interaction of CAD subunits.  (+info)

Aspartate carbamoyltransferase (ACT) is a crucial enzyme in the urea cycle, which is the biochemical pathway responsible for the elimination of excess nitrogen waste from the body. This enzyme catalyzes the second step of the urea cycle, where it facilitates the transfer of a carbamoyl group from carbamoyl phosphate to aspartic acid, forming N-acetylglutamic semialdehyde and releasing phosphate in the process.

The reaction catalyzed by aspartate carbamoyltransferase is as follows:

Carbamoyl phosphate + L-aspartate → N-acetylglutamic semialdehyde + P\_i + CO\_2

This enzyme plays a critical role in maintaining nitrogen balance and preventing the accumulation of toxic levels of ammonia in the body. Deficiencies or mutations in aspartate carbamoyltransferase can lead to serious metabolic disorders, such as citrullinemia and hyperammonemia, which can have severe neurological consequences if left untreated.

Ornithine carbamoyltransferase (OCT or OAT) is an enzyme that plays a crucial role in the urea cycle, which is the biochemical pathway responsible for the removal of excess nitrogen from the body. Specifically, ornithine carbamoyltransferase catalyzes the transfer of a carbamoyl group from carbamoyl phosphate to ornithine, forming citrulline and releasing phosphate in the process. This reaction is essential for the production of urea, which can then be excreted by the kidneys.

Deficiency in ornithine carbamoyltransferase can lead to a genetic disorder called ornithine transcarbamylase deficiency (OTCD), which is characterized by hyperammonemia (elevated blood ammonia levels) and neurological symptoms. OTCD is one of the most common urea cycle disorders, and it primarily affects females due to its X-linked inheritance pattern.

Dihydroorotase is an enzyme that plays a crucial role in the synthesis of pyrimidines, which are essential components of nucleic acids such as DNA and RNA. Specifically, dihydroorotase catalyzes the conversion of N-carbamoyl-L-aspartate into L-dihydroorotate and L-carbamoyl aspartate in the third step of de novo pyrimidine biosynthesis.

The reaction catalyzed by dihydroorotase is:

N-carbamoyl-L-aspartate + H2O → L-dihydroorotate + L-carbamoyl aspartate

Dihydroorotase is a member of the amidohydrolase superfamily and functions as a homodimer or homotetramer. In humans, dihydroorotase is encoded by the DHODH gene and is found in the cytoplasm of cells. Defects in this enzyme can lead to a rare genetic disorder called dihydropyrimidine dehydrogenase deficiency, which is characterized by an accumulation of pyrimidines and their precursors in the body.

Carbamyl Phosphate is a chemical compound that plays a crucial role in the biochemical process of nitrogen metabolism, particularly in the urea cycle. It is synthesized in the liver and serves as an important intermediate in the conversion of ammonia to urea, which is then excreted by the kidneys.

In medical terms, Carbamyl Phosphate Synthetase I (CPS I) deficiency is a rare genetic disorder that affects the production of Carbamyl Phosphate. This deficiency can lead to hyperammonemia, which is an excess of ammonia in the bloodstream, and can cause severe neurological symptoms and brain damage if left untreated.

It's important to note that while Carbamyl Phosphate is a critical component of the urea cycle, it is not typically used as a medication or therapeutic agent in clinical practice.

Cytidine triphosphate (CTP) is a nucleotide that plays a crucial role in the synthesis of RNA. It consists of a cytosine base, a ribose sugar, and three phosphate groups. Cytidine triphosphate is one of the four main building blocks of RNA, along with adenosine triphosphate (ATP), guanosine triphosphate (GTP), and uridine triphosphate (UTP). These nucleotides are essential for various cellular processes, including energy transfer, signal transduction, and biosynthesis. CTP is also involved in the regulation of several metabolic pathways and serves as a cofactor for enzymes that catalyze biochemical reactions. Like other triphosphate nucleotides, CTP provides energy for cellular functions by donating its phosphate groups in energy-consuming processes.

Phosphonoacetic acid (PAA) is not a naturally occurring substance, but rather a synthetic compound that is used in medical and scientific research. It is a colorless, crystalline solid that is soluble in water.

In a medical context, PAA is an inhibitor of certain enzymes that are involved in the replication of viruses, including HIV. It works by binding to the active site of these enzymes and preventing them from carrying out their normal functions. As a result, PAA has been studied as a potential antiviral agent, although it is not currently used as a medication.

It's important to note that while PAA has shown promise in laboratory studies, its safety and efficacy have not been established in clinical trials, and it is not approved for use as a drug by regulatory agencies such as the U.S. Food and Drug Administration (FDA).

"Moritella" is a genus of gram-negative, rod-shaped bacteria that are commonly found in marine environments. Some species of Moritella are psychrophilic, meaning they prefer cold temperatures and can be found in deep sea sediments and polar ice caps. The type species, Moritella marina, is an important pathogen in fish, causing a disease known as "cold water fish disease" or "winter ulcer disease." This disease is characterized by the formation of ulcers on the skin and muscles of fish, particularly in cold water temperatures. In humans, Moritella species are not typically considered to be pathogenic, but there have been rare cases of infection associated with wound contamination or exposure to contaminated seawater.

Dihydroorotate oxidase is a mitochondrial enzyme that plays a crucial role in the de novo biosynthesis of pyrimidines, which are essential nucleotides required for the synthesis of DNA, RNA, and other vital molecules in the body.

The enzyme catalyzes the oxidation of dihydroorotate to orotate, using molecular oxygen as an electron acceptor. This reaction is the third step in the pyrimidine biosynthesis pathway, following the condensation of carbamoyl phosphate and aspartate to form carbamoylaspartate, and the decarboxylation of carbamoylaspartate to form dihydroorotate.

Dihydroorotate oxidase is a flavoprotein that contains a FAD cofactor, which accepts electrons from dihydroorotate and transfers them to molecular oxygen, generating hydrogen peroxide as a byproduct. The enzyme is inhibited by the drug leflunomide, which is used in the treatment of rheumatoid arthritis and other autoimmune diseases.

In humans, dihydroorotate oxidase is encoded by two genes, DHODH and SUOX, which are located on different chromosomes. Mutations in these genes can lead to deficiencies in pyrimidine biosynthesis and result in various genetic disorders, such as Miller syndrome, a rare autosomal recessive disorder characterized by craniofacial abnormalities, limb defects, and hearing loss.

Aspartic acid is an α-amino acid with the chemical formula HO2CCH(NH2)CO2H. It is one of the twenty standard amino acids, and it is a polar, negatively charged, and hydrophilic amino acid. In proteins, aspartic acid usually occurs in its ionized form, aspartate, which has a single negative charge.

Aspartic acid plays important roles in various biological processes, including metabolism, neurotransmitter synthesis, and energy production. It is also a key component of many enzymes and proteins, where it often contributes to the formation of ionic bonds and helps stabilize protein structure.

In addition to its role as a building block of proteins, aspartic acid is also used in the synthesis of other important biological molecules, such as nucleotides, which are the building blocks of DNA and RNA. It is also a component of the dipeptide aspartame, an artificial sweetener that is widely used in food and beverages.

Like other amino acids, aspartic acid is essential for human health, but it cannot be synthesized by the body and must be obtained through the diet. Foods that are rich in aspartic acid include meat, poultry, fish, dairy products, eggs, legumes, and some fruits and vegetables.

Allosteric regulation is a process that describes the way in which the binding of a molecule (known as a ligand) to an enzyme or protein at one site affects the ability of another molecule to bind to a different site on the same enzyme or protein. This interaction can either enhance (positive allosteric regulation) or inhibit (negative allosteric regulation) the activity of the enzyme or protein, depending on the nature of the ligand and its effect on the shape and/or conformation of the enzyme or protein.

In an allosteric regulatory system, the binding of the first molecule to the enzyme or protein causes a conformational change in the protein structure that alters the affinity of the second site for its ligand. This can result in changes in the activity of the enzyme or protein, allowing for fine-tuning of biochemical pathways and regulatory processes within cells.

Allosteric regulation is a fundamental mechanism in many biological systems, including metabolic pathways, signal transduction cascades, and gene expression networks. Understanding allosteric regulation can provide valuable insights into the mechanisms underlying various physiological and pathological processes, and can inform the development of novel therapeutic strategies for the treatment of disease.

X-ray diffraction (XRD) is not strictly a medical definition, but it is a technique commonly used in the field of medical research and diagnostics. XRD is a form of analytical spectroscopy that uses the phenomenon of X-ray diffraction to investigate the crystallographic structure of materials. When a beam of X-rays strikes a crystal, it is scattered in specific directions and with specific intensities that are determined by the arrangement of atoms within the crystal. By measuring these diffraction patterns, researchers can determine the crystal structures of various materials, including biological macromolecules such as proteins and viruses.

In the medical field, XRD is often used to study the structure of drugs and drug candidates, as well as to analyze the composition and structure of tissues and other biological samples. For example, XRD can be used to investigate the crystal structures of calcium phosphate minerals in bone tissue, which can provide insights into the mechanisms of bone formation and disease. Additionally, XRD is sometimes used in the development of new medical imaging techniques, such as phase-contrast X-ray imaging, which has the potential to improve the resolution and contrast of traditional X-ray images.

'Escherichia coli' (E. coli) is a type of gram-negative, facultatively anaerobic, rod-shaped bacterium that commonly inhabits the intestinal tract of humans and warm-blooded animals. It is a member of the family Enterobacteriaceae and one of the most well-studied prokaryotic model organisms in molecular biology.

While most E. coli strains are harmless and even beneficial to their hosts, some serotypes can cause various forms of gastrointestinal and extraintestinal illnesses in humans and animals. These pathogenic strains possess virulence factors that enable them to colonize and damage host tissues, leading to diseases such as diarrhea, urinary tract infections, pneumonia, and sepsis.

E. coli is a versatile organism with remarkable genetic diversity, which allows it to adapt to various environmental niches. It can be found in water, soil, food, and various man-made environments, making it an essential indicator of fecal contamination and a common cause of foodborne illnesses. The study of E. coli has contributed significantly to our understanding of fundamental biological processes, including DNA replication, gene regulation, and protein synthesis.

Carboxyl transferases and carbamoyl transferases are two types of enzymes that play a crucial role in various metabolic pathways by transferring a carboxyl or carbamoyl group from one molecule to another. Here are the medical definitions for both:

1. Carboxyl Transferases: These are a class of enzymes that catalyze the transfer of a carboxyl group (-COOH) from one molecule to another. They play an essential role in several metabolic processes, such as the synthesis and degradation of amino acids, carbohydrates, lipids, and other biomolecules. One example of a carboxyl transferase is pyruvate carboxylase, which catalyzes the addition of a carboxyl group to pyruvate, forming oxaloacetate in the gluconeogenesis pathway.
2. Carbamoyl Transferases: These are enzymes that facilitate the transfer of a carbamoyl group (-CONH2) from one molecule to another. They participate in various metabolic reactions, including the synthesis of essential compounds like arginine, pyrimidines, and urea. An example of a carbamoyl transferase is ornithine carbamoyltransferase (OCT), which catalyzes the transfer of a carbamoyl group from carbamoyl phosphate to ornithine during the urea cycle.

Both carboxyl and carbamoyl transferases are vital for maintaining proper cellular function and homeostasis in living organisms, including humans. Dysregulation or deficiency of these enzymes can lead to various metabolic disorders and diseases.

Ornithine Carbamoyltransferase (OCT) Deficiency Disease, also known as Ornithine Transcarbamylase Deficiency, is a rare inherited urea cycle disorder. It is caused by a deficiency of the enzyme ornithine carbamoyltransferase, which is responsible for one of the steps in the urea cycle that helps to rid the body of excess nitrogen (in the form of ammonia).

When OCT function is impaired, nitrogen accumulates and forms ammonia, leading to hyperammonemia (elevated blood ammonia levels), which can cause neurological symptoms such as lethargy, vomiting, irritability, and in severe cases, coma or death.

Symptoms of OCT deficiency can range from mild to severe and may include developmental delay, seizures, behavioral changes, and movement disorders. The diagnosis is typically made through newborn screening tests, enzyme assays, and genetic testing. Treatment usually involves a combination of dietary restrictions, medications that help remove nitrogen from the body, and in some cases, liver transplantation.

Protein conformation refers to the specific three-dimensional shape that a protein molecule assumes due to the spatial arrangement of its constituent amino acid residues and their associated chemical groups. This complex structure is determined by several factors, including covalent bonds (disulfide bridges), hydrogen bonds, van der Waals forces, and ionic bonds, which help stabilize the protein's unique conformation.

Protein conformations can be broadly classified into two categories: primary, secondary, tertiary, and quaternary structures. The primary structure represents the linear sequence of amino acids in a polypeptide chain. The secondary structure arises from local interactions between adjacent amino acid residues, leading to the formation of recurring motifs such as α-helices and β-sheets. Tertiary structure refers to the overall three-dimensional folding pattern of a single polypeptide chain, while quaternary structure describes the spatial arrangement of multiple folded polypeptide chains (subunits) that interact to form a functional protein complex.

Understanding protein conformation is crucial for elucidating protein function, as the specific three-dimensional shape of a protein directly influences its ability to interact with other molecules, such as ligands, nucleic acids, or other proteins. Any alterations in protein conformation due to genetic mutations, environmental factors, or chemical modifications can lead to loss of function, misfolding, aggregation, and disease states like neurodegenerative disorders and cancer.

Ornithine is not a medical condition but a naturally occurring alpha-amino acid, which is involved in the urea cycle, a process that eliminates ammonia from the body. Here's a brief medical/biochemical definition of Ornithine:

Ornithine (NH₂-CH₂-CH₂-CH(NH₃)-COOH) is an α-amino acid without a carbon atom attached to the amino group, classified as a non-proteinogenic amino acid because it is not encoded by the standard genetic code and not commonly found in proteins. It plays a crucial role in the urea cycle, where it helps convert harmful ammonia into urea, which can then be excreted by the body through urine. Ornithine is produced from the breakdown of arginine, another amino acid, via the enzyme arginase. In some medical and nutritional contexts, ornithine supplementation may be recommended to support liver function, wound healing, or muscle growth, but its effectiveness for these uses remains a subject of ongoing research and debate.

Aspartate aminotransferases (ASTs) are a group of enzymes found in various tissues throughout the body, including the heart, liver, and muscles. They play a crucial role in the metabolic process of transferring amino groups between different molecules.

In medical terms, AST is often used as a blood test to measure the level of this enzyme in the serum. Elevated levels of AST can indicate damage or injury to tissues that contain this enzyme, such as the liver or heart. For example, liver disease, including hepatitis and cirrhosis, can cause elevated AST levels due to damage to liver cells. Similarly, heart attacks can also result in increased AST levels due to damage to heart muscle tissue.

It is important to note that an AST test alone cannot diagnose a specific medical condition, but it can provide valuable information when used in conjunction with other diagnostic tests and clinical evaluation.

L-Citrulline is a non-essential amino acid that plays a role in the urea cycle, which is the process by which the body eliminates toxic ammonia from the bloodstream. It is called "non-essential" because it can be synthesized by the body from other compounds, such as L-Ornithine and carbamoyl phosphate.

Citrulline is found in some foods, including watermelon, bitter melon, and certain types of sausage. It is also available as a dietary supplement. In the body, citrulline is converted to another amino acid called L-Arginine, which is involved in the production of nitric oxide, a molecule that helps dilate blood vessels and improve blood flow.

Citrulline has been studied for its potential benefits on various aspects of health, including exercise performance, cardiovascular function, and immune system function. However, more research is needed to confirm these potential benefits and establish safe and effective dosages.

Orotic acid, also known as pyrmidine carboxylic acid, is a organic compound that plays a role in the metabolic pathway for the biosynthesis of pyrimidines, which are nitrogenous bases found in nucleotides and nucleic acids such as DNA and RNA. Orotic acid is not considered to be a vitamin, but it is sometimes referred to as vitamin B13 or B15, although these designations are not widely recognized by the scientific community.

In the body, orotic acid is converted into orotidine monophosphate (OMP) by the enzyme orotate phosphoribosyltransferase. OMP is then further metabolized to form uridine monophosphate (UMP), a pyrimidine nucleotide that is an important precursor for the synthesis of RNA and other molecules.

Elevated levels of orotic acid in the urine, known as orotic aciduria, can be a sign of certain genetic disorders that affect the metabolism of pyrimidines. These conditions can lead to an accumulation of orotic acid and other pyrimidine precursors in the body, which can cause a range of symptoms including developmental delays, neurological problems, and kidney stones. Treatment for these disorders typically involves dietary restrictions and supplementation with nucleotides or nucleosides to help support normal pyrimidine metabolism.

Ornithine-oxo-acid transaminase (OAT), also known as ornithine aminotransferase, is a urea cycle enzyme that catalyzes the reversible transfer of an amino group from ornithine to α-ketoglutarate, producing glutamate semialdehyde and glutamate. This reaction is an essential part of the urea cycle, which is responsible for the detoxification of ammonia in the body. Deficiencies in OAT can lead to a genetic disorder called ornithine transcarbamylase deficiency (OTCD), which can cause hyperammonemia and neurological symptoms.

Hydrolases are a class of enzymes that help facilitate the breakdown of various types of chemical bonds through a process called hydrolysis, which involves the addition of water. These enzymes catalyze the cleavage of bonds in substrates by adding a molecule of water, leading to the formation of two or more smaller molecules.

Hydrolases play a crucial role in many biological processes, including digestion, metabolism, and detoxification. They can act on a wide range of substrates, such as proteins, lipids, carbohydrates, and nucleic acids, breaking them down into smaller units that can be more easily absorbed or utilized by the body.

Examples of hydrolases include:

1. Proteases: enzymes that break down proteins into smaller peptides or amino acids.
2. Lipases: enzymes that hydrolyze lipids, such as triglycerides, into fatty acids and glycerol.
3. Amylases: enzymes that break down complex carbohydrates, like starches, into simpler sugars, such as glucose.
4. Nucleases: enzymes that cleave nucleic acids, such as DNA or RNA, into smaller nucleotides or oligonucleotides.
5. Phosphatases: enzymes that remove phosphate groups from various substrates, including proteins and lipids.
6. Esterases: enzymes that hydrolyze ester bonds in a variety of substrates, such as those found in some drugs or neurotransmitters.

Hydrolases are essential for maintaining proper cellular function and homeostasis, and their dysregulation can contribute to various diseases and disorders.

Argininosuccinate Lyase is an enzyme that plays a crucial role in the urea cycle, which is the metabolic pathway responsible for eliminating excess nitrogen waste from the body. This enzyme is responsible for catalyzing the conversion of argininosuccinate into arginine and fumarate.

The urea cycle occurs primarily in the liver and helps to convert toxic ammonia, a byproduct of protein metabolism, into urea, which can be safely excreted in urine. Argininosuccinate lyase is essential for this process, as it helps to convert argininosuccinate, an intermediate compound in the cycle, into arginine, which can then be recycled back into the urea cycle or used for other physiological processes.

Deficiencies in argininosuccinate lyase can lead to a rare genetic disorder known as citrullinemia, which is characterized by elevated levels of citrulline and ammonia in the blood, as well as neurological symptoms such as seizures, developmental delays, and intellectual disability. Treatment for citrullinemia typically involves a low-protein diet, supplementation with arginine and other essential amino acids, and in some cases, liver transplantation.

Arginine is an α-amino acid that is classified as a semi-essential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. The adult human body can normally synthesize sufficient amounts of arginine to meet its needs, but there are certain circumstances, such as periods of rapid growth or injury, where the dietary intake of arginine may become necessary.

The chemical formula for arginine is C6H14N4O2. It has a molecular weight of 174.20 g/mol and a pKa value of 12.48. Arginine is a basic amino acid, which means that it contains a side chain with a positive charge at physiological pH levels. The side chain of arginine is composed of a guanidino group, which is a functional group consisting of a nitrogen atom bonded to three methyl groups.

In the body, arginine plays several important roles. It is a precursor for the synthesis of nitric oxide, a molecule that helps regulate blood flow and immune function. Arginine is also involved in the detoxification of ammonia, a waste product produced by the breakdown of proteins. Additionally, arginine can be converted into other amino acids, such as ornithine and citrulline, which are involved in various metabolic processes.

Foods that are good sources of arginine include meat, poultry, fish, dairy products, nuts, seeds, and legumes. Arginine supplements are available and may be used for a variety of purposes, such as improving exercise performance, enhancing wound healing, and boosting immune function. However, it is important to consult with a healthcare provider before taking arginine supplements, as they can interact with certain medications and have potential side effects.

Arginase is an enzyme that plays a role in the metabolism of arginine, an amino acid. It works by breaking down arginine into ornithine and urea. This reaction is part of the urea cycle, which helps to rid the body of excess nitrogen waste produced during the metabolism of proteins. Arginase is found in various tissues throughout the body, including the liver, where it plays a key role in the detoxification of ammonia.

Sodium benzoate is a chemical compound with the formula NaC7H5O2. It is a white crystalline powder that is readily soluble in water and alcohol. Sodium benzoate is a preservative commonly added to foods, beverages, and pharmaceuticals to inhibit microbial growth.

In medical terms, sodium benzoate may also be used as a medication to treat certain metabolic disorders such as hyperammonemia, which can occur in conditions like urea cycle disorders or liver disease. In these cases, sodium benzoate acts by binding with excess ammonia in the body and converting it into a compound that can be excreted through the kidneys.

It is important to note that people with a rare genetic disorder called benzoic aciduria should avoid foods or medications containing sodium benzoate, as they are unable to metabolize this compound properly.

Arsenates are salts or esters of arsenic acid (AsO4). They contain the anion AsO4(3-), which consists of an arsenic atom bonded to four oxygen atoms in a tetrahedral arrangement. Arsenates can be found in various minerals, and they have been used in pesticides, wood preservatives, and other industrial applications. However, arsenic is highly toxic to humans and animals, so exposure to arsenates should be limited. Long-term exposure to arsenic can cause skin lesions, cancer, and damage to the nervous system, among other health problems.

Transferases are a class of enzymes that facilitate the transfer of specific functional groups (like methyl, acetyl, or phosphate groups) from one molecule (the donor) to another (the acceptor). This transfer of a chemical group can alter the physical or chemical properties of the acceptor molecule and is a crucial process in various metabolic pathways. Transferases play essential roles in numerous biological processes, such as biosynthesis, detoxification, and catabolism.

The classification of transferases is based on the type of functional group they transfer:

1. Methyltransferases - transfer a methyl group (-CH3)
2. Acetyltransferases - transfer an acetyl group (-COCH3)
3. Aminotransferases or Transaminases - transfer an amino group (-NH2 or -NHR, where R is a hydrogen atom or a carbon-containing group)
4. Glycosyltransferases - transfer a sugar moiety (a glycosyl group)
5. Phosphotransferases - transfer a phosphate group (-PO3H2)
6. Sulfotransferases - transfer a sulfo group (-SO3H)
7. Acyltransferases - transfer an acyl group (a fatty acid or similar molecule)

These enzymes are identified and named according to the systematic nomenclature of enzymes developed by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB). The naming convention includes the class of enzyme, the specific group being transferred, and the molecules involved in the transfer reaction. For example, the enzyme that transfers a phosphate group from ATP to glucose is named "glucokinase."

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Transaminases, also known as aminotransferases, are a group of enzymes found in various tissues of the body, particularly in the liver, heart, muscle, and kidneys. They play a crucial role in the metabolism of amino acids, the building blocks of proteins.

There are two major types of transaminases: aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Both enzymes are normally present in low concentrations in the bloodstream. However, when tissues that contain these enzymes are damaged or injured, such as during liver disease or muscle damage, the levels of AST and ALT in the blood may significantly increase.

Measurement of serum transaminase levels is a common laboratory test used to assess liver function and detect liver injury or damage. Increased levels of these enzymes in the blood can indicate conditions such as hepatitis, liver cirrhosis, drug-induced liver injury, heart attack, and muscle disorders. It's important to note that while elevated transaminase levels may suggest liver disease, they do not specify the type or cause of the condition, and further diagnostic tests are often required for accurate diagnosis and treatment.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

"Pyrococcus furiosus" is not a medical term, but a scientific name for an extremophilic archaea species. It's a type of microorganism that thrives in extreme environments, particularly high temperature and acidity. "Pyrococcus furiosus" was first isolated from a marine volcanic vent and has since been studied extensively due to its unique biological properties.

In terms of scientific definition:

"Pyrococcus furiosus" is a species of archaea belonging to the order Thermococcales, family Pyrococcaceae. It's a hyperthermophilic organism, with an optimum growth temperature of around 100°C (212°F), and can survive in temperatures up to 106°C (223°F). The cells are irregularly coccoid, about 0.8-1.5 µm in diameter, and occur singly or in pairs.

The organism obtains energy by fermenting peptides and carbohydrates, producing hydrogen, carbon dioxide, and acetate as end products. "Pyrococcus furiosus" has been used as a model system for studying the biochemistry of archaea and extremophiles, including enzymes that function optimally at high temperatures.

Argininosuccinate synthase (ASS) is a urea cycle enzyme that plays a crucial role in the detoxification of ammonia in the body. This enzyme catalyzes the reaction that combines citrulline and aspartate to form argininosuccinate, which is subsequently converted to arginine and fumarate in the urea cycle.

The reaction catalyzed by argininosuccinate synthase is as follows:

Citrulline + Aspartate + ATP → Argininosuccinate + AMP + PPi

Deficiency in argininosuccinate synthase leads to a genetic disorder known as citrullinemia, which is characterized by an accumulation of ammonia in the blood and neurodevelopmental abnormalities. There are two forms of citrullinemia, type I and type II, with type I being more severe and caused by mutations in the ASS1 gene located on chromosome 9q34.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

... (also known as aspartate transcarbamoylase or ATCase) catalyzes the first step in the pyrimidine ... "2.5 A structure of aspartate carbamoyltransferase complexed with the bisubstrate analog N-(phosphonacetyl)-L-aspartate". ... Aspartate+carbamoyltransferase at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Portal: Biology (CS1 ... Two catalytic trimers and two regulatory dimers assemble to form an intermediate of aspartate carbamoyltransferase consisting ...
Aspartate carbamoyltransferase performs a step in building the pyrimidine nucleotides (cytosine and thymidine). Aspartate ... as activator and inhibitor molecules attach to aspartate carbamoyltransferase to speed it up and to slow it down. Aspartate ... Aspartate carbamoyltransferase. (right) was the second protein structure from Lipscomb's group. For a copy of DNA to be made, a ... Aspartate carbamoyltransferase was a much larger molecule than anything solved previously. Leucine aminopeptidase, (left) a ...
Aspartate carbamoyltransferase has a α6β6 subunit composition. The six αβ-protomers are arranged in D3 symmetry. Viral capsid ...
Aspartate carbamoyltransferase condenses carbamoyl phosphate with aspartate to form uridosuccinate. Dihydroorotase performs ... The biosynthesis of aspartate is a one step reaction that is catalyzed by a single enzyme. The enzyme aspartate ... The aspartate family of amino acids includes: threonine, lysine, methionine, isoleucine, and aspartate. Lysine and isoleucine ... Aspartate semialdehyde dehydrogenase catalyzes the NADPH-dependent reduction of aspartyl phosphate to yield aspartate ...
"Crystal and molecular structures of native and CTP-liganded aspartate carbamoyltransferase from Escherichia coli". Journal of ... Another enzyme that has been suggested early to bind ligands cooperatively is aspartate trans-carbamylase. Although initial ... Changeux JP, Rubin MM (February 1968). "Allosteric interactions in aspartate transcarbamylase. 3. Interpretation of ...
CTP acts as an inhibitor of the enzyme aspartate carbamoyltransferase, which is used in pyrimidine biosynthesis. CTP synthase ...
... coli enzyme aspartate carbamoyltransferase (ATCase) has become another good example of allosteric regulation. The kinetic ...
Next, aspartate carbamoyltransferase catalyzes a condensation reaction between aspartate and carbamoyl phosphate to form ... This new carbon is modified by the addition of a third NH2 unit, this time transferred from an aspartate residue. Finally, a ... First, GTP hydrolysis fuels the addition of aspartate to IMP by adenylosuccinate synthase, substituting the carbonyl oxygen for ... Pyrimidines are synthesized first from aspartate and carbamoyl-phosphate in the cytoplasm to the common precursor ring ...
... aspartate carbamoyltransferase and dihydroorotase. Dihydroorotate dehydrogenase (DHODH) unlike CAD and UMPS is a mono- ... "Entrez Gene: CAD carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase". "Entrez Gene: DHODH ...
... aspartate carbamoyltransferase. This must have involved a double fusion, a rare pair of events, supporting the shared ancestry ...
"Crystal Structures of Aspartate Carbamoyltransferase Li gated with Phosphonoacetamide, Malonate and CTP or ATP at 2.8-A ... "Escherichia coli aspartate carbamoyltransferase: The probing of crystal structure analysis via site-specific mutagenesis," ... "Crystal structure of the Glu-239 to Gln mutant of aspartate carbamoyltransferase at 3.1 A resolution: An intermediate ... "Structural Consequences of Effector Binding to the T State of Aspartate Carbamoyltransferase Crystal Structures of the ...
Noteworthy in this effort was that Wiley managed to grow crystals of aspartate carbamoyltransferase suitable for obtaining its ... There, Wiley did early work on the structure of aspartate carbamoyltransferase, the largest molecular structure determined at ...
... and aspartate carbamoyltransferase (EC 2.1.3.2), each the largest atomic structure determined in its time. Steitz did ... The structure of aspartate transcarbamylase, I. A molecular twofold axis in the complex with cytidine triphosphate. Proc Natl ...
... aspartate carbamoyltransferase EC 2.1.3.3: ornithine carbamoyltransferase EC 2.1.3.4: deleted EC 2.1.3.5: oxamate ... putrescine carbamoyltransferase EC 2.1.3.7: 3-hydroxymethylcephem carbamoyltransferase EC 2.1.3.8: lysine carbamoyltransferase ... N-succinylornithine carbamoyltransferase EC 2.1.3.13: The enzyme has been replaced by EC 6.1.2.2 EC 2.1.3.14: The enzyme has ... aspartate kinase EC 2.7.2.5: Now EC 6.3.4.16, carbamoyl-phosphate synthase (ammonia) EC 2.7.2.6: formate kinase EC 2.7.2.7: ...
... aspartate carbamoyltransferase MeSH D08.811.913.555.275.600 - ornithine carbamoyltransferase MeSH D08.811.913.555.400 - ... aspartate carbamoyltransferase MeSH D08.811.600.130 - aspartokinase homoserine dehydrogenase MeSH D08.811.600.200 - cholesterol ... aspartate aminotransferases MeSH D08.811.913.477.700.225.249 - aspartate aminotransferase, cytoplasmic MeSH D08.811.913.477. ... aspartate-tRNA ligase MeSH D08.811.464.263.200.250 - glutamate-trna ligase MeSH D08.811.464.263.200.350 - glycine-trna ligase ...
... and aspartate carbamoyltransferase that is not present in plants, and plants have a fusion of thymidylate synthase and ...
In ATCase such a transfer is written as carbamoyl phosphate + L-aspartate → {\displaystyle \rightarrow } L-carbamoyl aspartate ... "carbamoyltransferase". The Free Dictionary. Farlex, Inc. Retrieved 25 November 2013. "carbamoyl group (CHEBI:23004)". ChEBI: ... Kirsch JF, Eichele G, Ford GC, Vincent MG, Jansonius JN, Gehring H, Christen P (Apr 1984). "Mechanism of action of aspartate ... Reichard P, Hanshoff G (1956). "Aspartate Carbamyl Transferase from Escherichia coli" (PDF). Acta Chemica Scandinavica. 10: 548 ...
Rat ends with Ser, bovine with aspartate, and human with glycine. The human OTC gene is located on the short arm of chromosome ... Strautnieks S, Rutland P, Malcolm S (December 1991). "Arginine 109 to glutamine mutation in a girl with ornithine carbamoyl transferase ... Ornithine transcarbamylase (OTC) (also called ornithine carbamoyltransferase) is an enzyme (EC 2.1.3.3) that catalyzes the ... "The crystal structures of ornithine carbamoyltransferase from Mycobacterium tuberculosis and its ternary complex with carbamoyl ...
Due to above-average rates of PPP in individuals experiencing immunologic complications such as anti-N-methyl-D-aspartate (NMDA ... Cases have been described in carbamoyl phosphate synthetase 1, argino-succinate synthetase and ornithine carbamoyltransferase ... Postpartum anti-N-methyl-D-aspartate receptor encephalitis: a case report and literature review. Internal Medicine 56: 357-362 ...

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