Tryptophan
An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
Tryptophan Oxygenase
A dioxygenase with specificity for the oxidation of the indoleamine ring of TRYPTOPHAN. It is a LIVER-specific enzyme that is the first and rate limiting enzyme in the kynurenine pathway of TRYPTOPHAN catabolism.
Tryptophan Synthase
An enzyme that catalyzes the conversion of L-serine and 1-(indol-3-yl)glycerol 3-phosphate to L-tryptophan and glyceraldehyde 3-phosphate. It is a pyridoxal phosphate protein that also catalyzes the conversion of serine and indole into tryptophan and water and of indoleglycerol phosphate into indole and glyceraldehyde phosphate. (From Enzyme Nomenclature, 1992) EC 4.2.1.20.
Tryptophan Hydroxylase
An enzyme that catalyzes the hydroxylation of TRYPTOPHAN to 5-HYDROXYTRYPTOPHAN in the presence of NADPH and molecular oxygen. It is important in the biosynthesis of SEROTONIN.
Kynurenine
Kynurenine is a metabolic product of the amino acid tryptophan, formed via the kynurenine pathway, and serves as an important intermediate in the biosynthesis of nicotinamide adenine dinucleotide (NAD+) and other neuroactive compounds, while also playing a role in immune response regulation and potential involvement in various neurological disorders.
Bromosuccinimide
Spectrometry, Fluorescence
Measurement of the intensity and quality of fluorescence.
Indoleamine-Pyrrole 2,3,-Dioxygenase
A dioxygenase with specificity for the oxidation of the indoleamine ring of TRYPTOPHAN. It is an extrahepatic enzyme that plays a role in metabolism as the first and rate limiting enzyme in the kynurenine pathway of TRYPTOPHAN catabolism.
Anthranilate Synthase
ortho-Aminobenzoates
Acrylamide
Xanthurenates
Xanthurenic acid and its salts, formed as byproducts during the metabolism of tryptophan, are collectively referred to as xanthurenates, which can accumulate in conditions like hyperphenylalaninemia and may contribute to oxidative stress and cellular damage.
Amino Acids
Serotonin
A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.
Protein Conformation
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).
Hydroxyindoleacetic Acid
Tryptophanase
An enzyme that catalyzes the conversion of L-tryptophan and water to indole, pyruvate, and ammonia. It is a pyridoxal-phosphate protein, requiring K+. It also catalyzes 2,3-elimination and beta-replacement reactions of some indole-substituted tryptophan analogs of L-cysteine, L-serine, and other 3-substituted amino acids. (From Enzyme Nomenclature, 1992) EC 4.1.99.1.
3-Hydroxyanthranilic Acid
Circular Dichroism
Amino Acid Sequence
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.
Phenylalanine
Escherichia coli
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.
Molecular Sequence Data
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.
Binding Sites
Anthranilate Phosphoribosyltransferase
An enzyme that catalyzes the formation of N-5'-phosphoribosylanthranilic acid from anthranilate and phosphoribosylpyrophosphate, the first step in tryptophan synthesis in E. coli. It exists in a complex with ANTHRANILATE SYNTHASE in bacteria. EC 2.4.2.18.
Spectrophotometry, Ultraviolet
Models, Molecular
Fluorescence
The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
Tryptophan-tRNA Ligase
Indoles
Protein Binding
Kynurenine 3-Monooxygenase
An NADPH-dependent flavin monooxygenase that plays a key role in the catabolism of TRYPTOPHAN by catalyzing the HYDROXYLATION of KYNURENINE to 3-hydroxykynurenine. It was formerly characterized as EC 1.14.1.2 and EC 1.99.1.5.
Mutation
Mutagenesis, Site-Directed
Fluorescence Polarization
Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.
Quinolinic Acid
A metabolite of tryptophan with a possible role in neurodegenerative disorders. Elevated CSF levels of quinolinic acid are correlated with the severity of neuropsychological deficits in patients who have AIDS.
Niacin
5-Hydroxytryptophan
The immediate precursor in the biosynthesis of SEROTONIN from tryptophan. It is used as an antiepileptic and antidepressant.
Indolequinones
Acrylamides
Colorless, odorless crystals that are used extensively in research laboratories for the preparation of polyacrylamide gels for electrophoresis and in organic synthesis, and polymerization. Some of its polymers are used in sewage and wastewater treatment, permanent press fabrics, and as soil conditioning agents.
Quinolinic Acids
Quinolinic acid is a physiologically occurring metabolite of the kynurenine pathway, involved in the metabolism of tryptophan, which functions as a neuroexcitatory agent and has been implicated in several neurological disorders, including Huntington's disease and HIV-associated dementia.
Operon
Protein Denaturation
RNA, Transfer, Trp
Energy Transfer
The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER.
Skatole
Tyrosine
A non-essential amino acid. In animals it is synthesized from PHENYLALANINE. It is also the precursor of EPINEPHRINE; THYROID HORMONES; and melanin.
Protein Structure, Secondary
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
Pellagra
A disease due to deficiency of NIACIN, a B-complex vitamin, or its precursor TRYPTOPHAN. It is characterized by scaly DERMATITIS which is often associated with DIARRHEA and DEMENTIA (the three D's).
Hydrogen-Ion Concentration
Base Sequence
Transaminases
Enzyme Repression
Amino Acid Transport Systems
Cellular proteins and protein complexes that transport amino acids across biological membranes.
Structure-Activity Relationship
Protein Structure, Tertiary
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Spectrophotometry
Oxidation-Reduction
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
Liver
Guanidine
A strong organic base existing primarily as guanidium ions at physiological pH. It is found in the urine as a normal product of protein metabolism. It is also used in laboratory research as a protein denaturant. (From Martindale, the Extra Pharmacopoeia, 30th ed and Merck Index, 12th ed) It is also used in the treatment of myasthenia and as a fluorescent probe in HPLC.