Spermine
Spermine Synthase
Polyamines
Spermidine
Putrescine
Biogenic Polyamines
Adenosylmethionine Decarboxylase
Spermidine Synthase
Ornithine Decarboxylase
Acetyltransferases
Eflornithine
Cyclohexylamines
Oxidoreductases Acting on CH-NH Group Donors
Magnesium
Phosvitin
Carboxy-Lyases
Overexpression of spermidine/spermine N1-acetyltransferase under the control of mouse metallothionein I promoter in transgenic mice: evidence for a striking post-transcriptional regulation of transgene expression by a polyamine analogue. (1/1393)
We recently generated a transgenic mouse line overexpressing spermidine/spermine N1-acetyltransferase (SSAT) gene under its own promoter. The tissue polyamine pools of these animals were profoundly affected and the mice were hairless from early age. We have now generated another transgenic-mouse line overexpressing the SSAT gene under the control of a heavy-metal-inducible mouse metallothionein I (MT) promoter. Even in the absence of heavy metals, changes in the tissue polyamine pools indicated that a marked activation of polyamine catabolism had occurred in the transgenic animals. As with the SSAT transgenic mice generated previously, the mice of the new line (MT-SSAT) suffered permanent hair loss, but this occurred considerably later than in the previous SSAT transgenic animals. Liver was the most affected tissue in the MT-SSAT transgenic animals, revealed by putrescine overaccumulation, significant decrease in spermidine concentration and >90% reduction in the spermine pool. Even though hepatic SSAT mRNA accumulated to massive levels in non-induced transgenic animals, SSAT activity was only moderately elevated. Administration of ZnSO4 further elevated the level of hepatic SSAT message and induced enzyme activity, but not more than 2- to 3-fold. Treatment of the transgenic animals with the polyamine analogue N1,N11-diethylnorspermine (DENSPM) resulted in an immense induction, more than 40000-fold, of enzyme activity in the liver of transgenic animals, and minor changes in the SSAT mRNA level. Liver spermidine and spermine pools were virtually depleted within 1-2 days in response to the treatment with the analogue. The treatment also resulted in a marked mortality (up to 60%) among the transgenic animals which showed ultrastructural changes in the liver, most notably mitochondrial swelling, one of the earliest signs of cell injury. These results indicated that, even without its own promoter, SSAT is powerfully induced by the polyamine analogue through a mechanism that appears to involve a direct translational and/or heterogenous nuclear RNA processing control. It is likewise significant that overexpression of SSAT renders the animals extremely sensitive to polyamine analogues. (+info)Proteoglycan involvement in polyamine uptake. (2/1393)
We have evaluated the possible role of proteoglycans in the uptake of spermine by human lung fibroblasts. Exogenous glycosaminoglycans behaved as competitive inhibitors of spermine uptake, the most efficient being heparan sulphate (Ki=0.16+/-0.04 microM). Treatment of fibroblasts with either heparan sulphate lyase, p-nitrophenyl-O-beta-D-xylopyranoside or chlorate reduced spermine uptake considerably, whereas chondroitin sulphate lyase had a limited effect. Inhibition of polyamine biosynthesis with alpha-difluoromethylornithine resulted in an increase of cell-associated heparan sulphate proteoglycans exhibiting higher affinity for spermine. The data indicate a specific role for heparan sulphate proteoglycans in the uptake of spermine by fibroblasts. Spermine uptake by pgsD-677, a mutant Chinese hamster ovary cell defective in heparan sulphate biosynthesis, was only moderately reduced (20%) compared with wild-type cells. Treatment of mutant cells with the above-mentioned xyloside resulted in a greater reduction of endogenous proteoglycan production as well as a higher inhibition of spermine uptake than in wild-type cells. Moreover, treatment with chondroitin sulphate lyase resulted in a selective inhibition of uptake in mutant cells, indicating a role for chondroitin/dermatan sulphate proteoglycans in the uptake of spermine by these cells. Fibroblasts, made growth-dependent on exogenous spermine by alpha-difluoromethylornithine treatment, were growth-inhibited by heparan sulphate or beta-D-xyloside, which might have future therapeutical implications. (+info)Distinct sensitivities of OmpF and PhoE porins to charged modulators. (3/1393)
The inhibition of the anion-selective PhoE porin by ATP and of the cation-selective OmpF porin by polyamines has been previously documented. In the present study, we have extended the comparison of the inhibitor-porin pairs by investigating the effect of anions (ATP and aspartate) and positively charged polyamines (spermine and cadaverine) on both OmpF and PhoE with the patch-clamp technique, and by comparing directly the gating kinetics of the channels modulated by their respective substrates. The novel findings reported here are (1) that the activity of PhoE is completely unaffected by polyamines, and (2) that the kinetic changes induced by ATP on PhoE or polyamines on OmpF suggest different mechanisms of inhibition. ATP induces a high degree of flickering in the PhoE-mediated current and appears to behave as a blocker of ion flow during its presumed transport through PhoE. Polyamines modulate the kinetics of openings and closings of OmpF, in addition to promoting a blocker-like flickering activity. The strong correlation between sensitivity to inhibitors and ion selectivity suggests that some common molecular determinants are involved in these two properties and is in agreement with the hypothesis that polyamines bind inside the pore of cationic porins. (+info)Polyamine analogue induction of the p53-p21WAF1/CIP1-Rb pathway and G1 arrest in human melanoma cells. (4/1393)
Although polyamines are well recognized for their critical involvement in cell growth, the cell cycle specificity of this requirement has not yet been characterized with respect to the newly delineated regulatory pathways. We recently reported that polyamine analogues having close structural and functional similarities to the natural polyamines produce a distinct G1 and G2-M cell cycle arrest in MALME-3M human melanoma cells. To determine a molecular basis for this observation, we examined the effects of N1,N11-diethylnorspermine on cell cycle regulatory proteins associated with G1 arrest. The analogue is known to deplete polyamine pools by suppressing biosynthetic enzymes and potently inducing the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase. Treatment of MALME-3M cells with 10 microM N1,N11-diethylnorspermine caused an increase in hypophosphorylated Rb, which correlated temporally with the onset of G1 arrest at 16-24 h. Rb hypophosphorylation was preceded by an increase in wild-type p53 (approximately 100-fold at maximum) and a concomitant increase in the cyclin-dependent kinase inhibitor, p21WAF1/CIP1 (p21; approximately 5-fold at maximum). Another cyclin-dependent kinase inhibitor, p27KIP1, and cyclin D increased slightly, whereas proliferating cell nuclear antigen and p130 remained unchanged. Induction of p21 protein was accompanied by an increase in p21 mRNA, whereas induction of p53 protein was not, suggesting transcriptional activation of the former and posttranscriptional regulation of the latter. SK-MEL-28 human melanoma cells, which contain a mutated p53, failed to induce p53 or p21 and did not arrest in G1. Rather, these cells rapidly underwent programmed cell death within 48 h. Overall, these findings provide the first indication of the cell cycle regulatory pathways by which polyamine antagonists such as analogues might inhibit growth in cells containing wild-type p53 and further suggest a mechanistic basis for differential cellular responses to these agents. (+info)Transgenic mice with activated polyamine catabolism due to overexpression of spermidine/spermine N1-acetyltransferase show enhanced sensitivity to the polyamine analog, N1, N11-diethylnorspermine. (5/1393)
We have recently generated transgenic mice in which polyamine catabolism has been activated by overexpressing the rate-limiting enzyme of polyamine catabolism, spermidine/spermine N1-acetyltransferase (SSAT). These animals have now been tested for their sensitivity to the polyamine analog N1,N11-diethylnorspermine (DENSPM), which is currently undergoing Phase I clinical trial. The analog is known for its ability to potently induce SSAT. Treatment for 4 days with a daily dose (125 mg/kg) of analog caused profound changes in polyamine metabolism in the transgenic animals. Liver SSAT activity was increased by approximately 800-fold while hepatic mRNA increased only 4-fold. Putrescine pools increased while spermidine and spermine pools nearly disappeared, resulting in a compensatory increase in ornithine decarboxylase activity. Similar but less profound changes were also seen in other tissues (spleen, intestine, and skin). This treatment also resulted in a 50% mortality in the transgenic animals, with no apparent histopathological changes in major organs. Nontransgenic animals exhibited no toxicity, and tissue SSAT activity was unchanged or only moderately increased. Polyamine pools were only slightly altered. Greater analog toxicity in transgenic animals may be attributable to higher tissue levels of DENSPM facilitated by SSAT-mediated decreases in spermidine and spermine. To further confirm the enhanced sensitivity of the transgenic animals to the analog, groups of nontransgenic and transgenic animals were subjected to daily injections with DENSPM. On average, transgenic mice died approximately 3 days earlier than their nontransgenic litter-mates. The findings indicate a contributing role for SSAT in whole animal toxicity by SSAT-inducing polyamine analogs. (+info)Lipopolyamines: novel antiendotoxin compounds that reduce mortality in experimental sepsis caused by gram-negative bacteria. (6/1393)
The interactions of lipopolyamines, a class of structurally unique compounds currently being used as transfection (lipofection) agents, with lipopolysaccharide (LPS) have been characterized. Our studies have demonstrated that 1,3-di-oleoyloxy-2-(6-carboxyspermyl)-propylamide), available commercially as DOSPER, binds to purified LPS with an affinity of about 1/10 that of polymyxin B. This essentially nontoxic compound inhibits, in a dose-dependent manner, LPS-induced activation of the Limulus clotting cascade and the production of tumor necrosis factor alpha (TNF-alpha) interleukin-6 (IL-6), and nitric oxide from LPS-stimulated J774.A1 cells, a murine macrophage-like cell line. Cytokine inhibition is paralleled by decreased steady-state levels of TNF-alpha and IL-6 mRNA and inhibits the nuclear translocation of nuclear factor kappa B. These findings suggest that the lipopolyamine compound sequesters LPS, thereby blocking downstream cellular activation events that lead to the production of proinflammatory mediators. Administration of DOSPER to D-galactosamine-sensitized mice challenged either with LPS or with Escherichia coli organisms provided significant protection against lethality both with and without antibiotic chemotherapy. Partial protection is evident in LPS-challenged mice treated with DOSPER as late as 2 to 4 h following the endotoxin challenge. A greater degree of protection is observed in E. coli-challenged animals receiving ceftazidime than in those receiving imipenem, which is probably attributable to the higher levels of LPS released in vivo by the former antibiotic. Potent antiendotoxic activity, low toxicity, and ease of synthesis render the lipopolyamines candidate endotoxin-sequestering agents of potential significant therapeutic value. (+info)A potent polyamine analog, spermindiol. (7/1393)
The effects of spermine, putrescine, and spermindiol on different nucleases were investigated. A highly active spermine analog, spermindiol, was synthesized, which markedly enhanced DNA hydrolysis by staphylococcal nuclease and spleen DNase II [EC 3.1.4.6] and RNA degradation by staphylococcal nuclease and pancreatic RNase A [EC 3.1.4.22]. Spermindiol also increased the melting temperature of calf thymus DNA. (+info)Polyamine-dependent deoxyribonuclease activity from rat-liver nuclei. (8/1393)
When nuclei isolated from rat liver in a low salt buffer were washed with 0.1 M NaCl solution, the supernatant showed a deoxyribonuclease (DNase) activity. The activity required Mg2+ and in addition spermine or spermidine, and its optimal pH was 7.2-7.4. The activity was higher on denatured (single stranded) DNA than on double-helical DNA. With both substrates the activity was highest at a polyamine concentration at which the DNA-polyamine complex began to precipitate. No Mg2++Ca2+ dependent DNase activity was detected in the preparation. (+info)Spermine is a polyamine compound that is involved in various biological processes, including cell growth and differentiation, DNA packaging, and gene expression. It is synthesized from the amino acid ornithine through a series of enzymatic reactions and is found in high concentrations in tissues such as the prostate gland, liver, and brain. Spermine has been shown to have antioxidant properties and may play a role in protecting cells against oxidative stress. In addition, spermine has been implicated in the regulation of ion channels and receptors, and may be involved in the modulation of neuronal excitability.
Spermine Synthase is an enzyme involved in the biosynthesis of polyamines. Polyamines are organic compounds with more than one amino group, and they play important roles in various cellular processes such as cell growth, differentiation, and apoptosis. Spermine Synthase specifically catalyzes the conversion of spermidine to spermine by adding an additional aminobutyl group to spermidine. This enzyme is widely distributed in various tissues and organisms, including humans, and its activity is tightly regulated in response to changes in cellular demands for polyamines.
Polyamines are organic compounds with more than one amino group (-NH2) and at least one carbon atom bonded to two or more amino groups. They are found in various tissues and fluids of living organisms and play important roles in many biological processes, such as cell growth, differentiation, and apoptosis (programmed cell death). Polyamines are also involved in the regulation of ion channels and transporters, DNA replication and gene expression. The most common polyamines found in mammalian cells are putrescine, spermidine, and spermine. They are derived from the decarboxylation of amino acids such as ornithine and methionine. Abnormal levels of polyamines have been associated with various pathological conditions, including cancer and neurodegenerative diseases.
Spermidine is a polycationic polyamine that is found in various tissues and fluids, including semen, from which it derives its name. It is synthesized in the body from putrescine, another polyamine, through the action of the enzyme spermidine synthase.
In addition to its role as a metabolic intermediate, spermidine has been shown to have various cellular functions, including regulation of gene expression, DNA packaging and protection, and modulation of enzymatic activities. It also plays a role in the process of cell division and differentiation.
Spermidine has been studied for its potential anti-aging effects, as it has been shown to extend the lifespan of various organisms, including yeast, flies, and worms, by activating autophagy, a process by which cells break down and recycle their own damaged or unnecessary components. However, more research is needed to determine whether spermidine has similar effects in humans.
Putrescine is an organic compound with the chemical formula NH2(CH2)4NH2. It is a colorless, viscous liquid that is produced by the breakdown of amino acids in living organisms and is often associated with putrefaction, hence its name. Putrescine is a type of polyamine, which is a class of organic compounds that contain multiple amino groups.
Putrescine is produced in the body through the decarboxylation of the amino acid ornithine by the enzyme ornithine decarboxylase. It is involved in various cellular processes, including the regulation of gene expression and cell growth. However, at high concentrations, putrescine can be toxic to cells and has been implicated in the development of certain diseases, such as cancer.
Putrescine is also found in various foods, including meats, fish, and some fruits and vegetables. It contributes to the unpleasant odor that develops during spoilage, which is why putrescine is often used as an indicator of food quality and safety.
Biogenic polyamines are organic compounds that contain multiple amino groups and are produced by living organisms. The most common biogenic polyamines found in mammalian cells include putrescine, spermidine, and spermine. These molecules play important roles in various cellular processes such as gene expression, cell growth, differentiation, and apoptosis (programmed cell death). They are derived from the decarboxylation of amino acids, particularly ornithine and arginine, through enzymatic reactions involving polyamine biosynthetic pathways. Abnormal levels of biogenic polyamines have been associated with several diseases, including cancer and neurodegenerative disorders.
Adenosylmethionine decarboxylase (AdoMetDC) is an enzyme that plays a crucial role in the biosynthesis of polyamines, which are essential molecules for cell growth and differentiation. The enzyme catalyzes the decarboxylation of S-adenosylmethionine (SAM) to produce decarboxylated SAM, also known as deoxyadenosylcobalamin or coenzyme M.
Decarboxylated SAM serves as an aminopropyl group donor in the biosynthesis of polyamines such as spermidine and spermine. These polyamines are involved in various cellular processes, including DNA replication, transcription, translation, protein synthesis, and cell signaling.
AdoMetDC is a pyridoxal-5'-phosphate (PLP)-dependent enzyme that requires the cofactor vitamin B12 for its activity. It is found in various organisms, including bacteria, yeast, plants, and animals. In humans, AdoMetDC is encoded by the AMD1 gene and is localized mainly in the cytosol of cells.
Dysregulation of AdoMetDC activity has been implicated in several diseases, such as cancer, neurodegenerative disorders, and cardiovascular diseases. Therefore, targeting AdoMetDC with inhibitors or activators has emerged as a potential therapeutic strategy for treating these conditions.
Spermidine synthase is an enzyme (EC 2.5.1.16) that catalyzes the synthesis of spermidine from putrescine and decarboxylated S-adenosylmethionine (dcSAM). This reaction is a part of the polyamine biosynthetic pathway, which plays a crucial role in cell growth and differentiation.
The reaction catalyzed by spermidine synthase can be represented as follows:
putrescine + dcSAM → spermidine + S-adenosylhomocysteine
In humans, there are two isoforms of spermidine synthase, namely, SRM and SMS. These isoforms share a common catalytic mechanism but differ in their subcellular localization and regulation. Mutations in the genes encoding spermidine synthase have been associated with certain diseases, such as cancer and neurological disorders.
Ornithine decarboxylase (ODC) is a medical/biochemical term that refers to an enzyme (EC 4.1.1.17) involved in the metabolism of amino acids, particularly ornithine. This enzyme catalyzes the decarboxylation of ornithine to form putrescine, which is a precursor for the synthesis of polyamines, such as spermidine and spermine. Polyamines play crucial roles in various cellular processes, including cell growth, differentiation, and gene expression.
Ornithine decarboxylase is a rate-limiting enzyme in polyamine biosynthesis, meaning that its activity regulates the overall production of these molecules. The regulation of ODC activity is tightly controlled at multiple levels, including transcription, translation, and post-translational modifications. Dysregulation of ODC activity has been implicated in several pathological conditions, such as cancer, neurodegenerative disorders, and inflammatory diseases.
Inhibitors of ornithine decarboxylase have been explored as potential therapeutic agents for various diseases, including cancer, due to their ability to suppress polyamine synthesis and cell proliferation. However, the use of ODC inhibitors in clinical settings has faced challenges related to toxicity and limited efficacy.
Acetyltransferases are a type of enzyme that facilitates the transfer of an acetyl group (a chemical group consisting of an acetyl molecule, which is made up of carbon, hydrogen, and oxygen atoms) from a donor molecule to a recipient molecule. This transfer of an acetyl group can modify the function or activity of the recipient molecule.
In the context of biology and medicine, acetyltransferases are important for various cellular processes, including gene expression, DNA replication, and protein function. For example, histone acetyltransferases (HATs) are a type of acetyltransferase that add an acetyl group to the histone proteins around which DNA is wound. This modification can alter the structure of the chromatin, making certain genes more or less accessible for transcription, and thereby influencing gene expression.
Abnormal regulation of acetyltransferases has been implicated in various diseases, including cancer, neurodegenerative disorders, and infectious diseases. Therefore, understanding the function and regulation of these enzymes is an important area of research in biomedicine.
Eflornithine is a antiprotozoal medication, which is used to treat sleeping sickness (human African trypanosomiasis) caused by Trypanosoma brucei gambiense in adults and children. It works by inhibiting the enzyme ornithine decarboxylase, which is needed for the growth of the parasite. By doing so, it helps to control the infection and prevent further complications.
Eflornithine is also used as a topical cream to slow down excessive hair growth in women due to a condition called hirsutism. It works by interfering with the growth of hair follicles.
It's important to note that Eflornithine should be used under the supervision of a healthcare professional, and it may have side effects or interactions with other medications.
Cyclohexylamines are a class of organic compounds that consist of a cyclohexane ring (a six-carbon saturated ring) with an amine group (-NH2, -NHR, or -NR2) attached to it. The amine group can be primary (one alkyl group attached to the nitrogen atom), secondary (two alkyl groups attached to the nitrogen atom), or tertiary (three alkyl groups attached to the nitrogen atom).
Cyclohexylamines have a wide range of applications in the chemical industry, including as intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. Some cyclohexylamines are also used as solvents or extractants. However, some cyclohexylamines can be toxic or have harmful effects on human health, so they must be handled with care.
'Diamines' are organic compounds containing two amino groups (-NH2) in their molecular structure. The term 'diamine' itself does not have a specific medical definition, but it is used in the context of chemistry and biochemistry.
Diamines can be classified based on the number of carbon atoms between the two amino groups. For example, ethylenediamine and propylenediamine are diamines with one and two methylene (-CH2-) groups, respectively.
In medicine, certain diamines may have biological significance. For instance, putrescine and cadaverine are polyamines that are produced during the decomposition of animal tissues and can be found in necrotic or infected tissues. These compounds have been implicated in various pathological processes, including inflammation, oxidative stress, and cancer progression.
It is important to note that while some diamines may have medical relevance, the term 'diamines' itself does not have a specific medical definition.
Oxidoreductases acting on CH-NH group donors are a class of enzymes within the larger group of oxidoreductases, which are responsible for catalyzing oxidation-reduction reactions. Specifically, this subclass of enzymes acts on CH-NH group donors, where the CH-NH group is a chemical functional group consisting of a carbon atom (C) bonded to a nitrogen atom (N) via a single covalent bond.
These enzymes play a crucial role in various biological processes by transferring electrons from the CH-NH group donor to an acceptor molecule, which results in the oxidation of the donor and reduction of the acceptor. This process can lead to the formation or breakdown of chemical bonds, and plays a key role in metabolic pathways such as amino acid degradation and nitrogen fixation.
Examples of enzymes that fall within this class include:
* Amino oxidases, which catalyze the oxidative deamination of amino acids to produce alpha-keto acids, ammonia, and hydrogen peroxide.
* Transaminases, which transfer an amino group from one molecule to another, often in the process of amino acid biosynthesis or degradation.
* Amine oxidoreductases, which catalyze the oxidation of primary amines to aldehydes and secondary amines to ketones, with the concomitant reduction of molecular oxygen to hydrogen peroxide.
Cadaverine is a foul-smelling organic compound that is produced by the breakdown of certain amino acids in dead bodies. It is formed through the decarboxylation of lysine, an essential amino acid, and is characterized by its strong, unpleasant odor. Cadaverine is often used as a forensic indicator of decomposition and is also being studied for its potential role in various physiological processes, such as inflammation and cancer.
Thionucleosides are a type of modified nucleoside where the oxygen atom in the sugar component (ribose or deoxyribose) is replaced by a sulfur atom. This modification can occur naturally or be introduced synthetically. The resulting compounds have been studied for their potential biological activity, including antiviral and anticancer properties. However, they are not typically used as a standard medical treatment at this time.
Magnesium is an essential mineral that plays a crucial role in various biological processes in the human body. It is the fourth most abundant cation in the body and is involved in over 300 enzymatic reactions, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium also contributes to the structural development of bones and teeth.
In medical terms, magnesium deficiency can lead to several health issues, such as muscle cramps, weakness, heart arrhythmias, and seizures. On the other hand, excessive magnesium levels can cause symptoms like diarrhea, nausea, and muscle weakness. Magnesium supplements or magnesium-rich foods are often recommended to maintain optimal magnesium levels in the body.
Some common dietary sources of magnesium include leafy green vegetables, nuts, seeds, legumes, whole grains, and dairy products. Magnesium is also available in various forms as a dietary supplement, including magnesium oxide, magnesium citrate, magnesium chloride, and magnesium glycinate.
Phosvitin is not a medical term, but it is a protein found in egg yolk. It is a highly phosphorylated protein, meaning that many of its amino acids are bound to phosphate groups. This gives phosvitin a high negative charge and makes it an excellent chelator of positively charged ions such as calcium and iron.
Phosvitin is known for its ability to bind and store minerals, particularly iron, in the egg yolk. It plays a role in the development and nutrition of growing embryos in birds. In addition to its nutritional role, phosvitin has been studied for its potential health benefits due to its antioxidant properties and ability to bind heavy metals.
While not a medical term itself, phosvitin may be relevant to certain medical fields such as nutrition, biochemistry, and food science.
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.
Carboxy-lyases are a class of enzymes that catalyze the removal of a carboxyl group from a substrate, often releasing carbon dioxide in the process. These enzymes play important roles in various metabolic pathways, such as the biosynthesis and degradation of amino acids, sugars, and other organic compounds.
Carboxy-lyases are classified under EC number 4.2 in the Enzyme Commission (EC) system. They can be further divided into several subclasses based on their specific mechanisms and substrates. For example, some carboxy-lyases require a cofactor such as biotin or thiamine pyrophosphate to facilitate the decarboxylation reaction, while others do not.
Examples of carboxy-lyases include:
1. Pyruvate decarboxylase: This enzyme catalyzes the conversion of pyruvate to acetaldehyde and carbon dioxide during fermentation in yeast and other organisms.
2. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO): This enzyme is essential for photosynthesis in plants and some bacteria, as it catalyzes the fixation of carbon dioxide into an organic molecule during the Calvin cycle.
3. Phosphoenolpyruvate carboxylase: Found in plants, algae, and some bacteria, this enzyme plays a role in anaplerotic reactions that replenish intermediates in the citric acid cycle. It catalyzes the conversion of phosphoenolpyruvate to oxaloacetate and inorganic phosphate.
4. Aspartate transcarbamylase: This enzyme is involved in the biosynthesis of pyrimidines, a class of nucleotides. It catalyzes the transfer of a carboxyl group from carbamoyl aspartate to carbamoyl phosphate, forming cytidine triphosphate (CTP) and fumarate.
5. Urocanase: Found in animals, this enzyme is involved in histidine catabolism. It catalyzes the conversion of urocanate to formiminoglutamate and ammonia.
Deoxyadenosine is a chemical compound that is a component of DNA, one of the nucleic acids that make up the genetic material of living organisms. Specifically, deoxyadenosine is a nucleoside, which is a molecule consisting of a sugar (in this case, deoxyribose) bonded to a nitrogenous base (in this case, adenine).
Deoxyribonucleosides like deoxyadenosine are the building blocks of DNA, along with phosphate groups. In DNA, deoxyadenosine pairs with thymidine via hydrogen bonds to form one of the four rungs in the twisted ladder structure of the double helix.
It is important to note that there is a similar compound called adenosine, which contains an extra oxygen atom on the sugar molecule (making it a ribonucleoside) and is a component of RNA, another nucleic acid involved in protein synthesis and other cellular processes.
