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Kynureninase
Kynureninase or L-Kynurenine hydrolase (KYNU) () is a PLP dependent enzyme that catalyses the cleavage of kynurenine (Kyn) into anthranilic acid (Ant). It can also act on 3-hydroxykynurenine (to produce 3-hydroxyanthranilate) and some other (3-arylcarbonyl)-alanines. Humans express one kynureninase enzyme that is encoded by the ''KYNU'' gene located on chromosome 2. KYNU is part of the pathway for the catabolism of Trp and the biosynthesis of NAD cofactors from tryptophan (Trp). Kynureninase catalyzes the following reaction: : L-kynurenine + H2O ↔ anthranilate + L-alanine Structure Kynureninase belongs to the class V group of aspartate aminotransferase superfamily of structurally homologous pyridoxal 5'-phosphate ( PLP) dependent enzymes. To date, two structures of human kynureninase have determined by X-ray diffraction with resolutions of 2.0 and 1.7 Å.; Forty percent of the amino acids are arranged in an alpha helical and twelve percent are arranged in beta sheets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynureninase Reaction
Kynureninase or L-Kynurenine hydrolase (KYNU) () is a Pyridoxal-phosphate, PLP dependent enzyme that catalyses the cleavage of kynurenine (Kyn) into anthranilic acid (Ant). It can also act on 3-hydroxykynurenine (to produce 3-hydroxyanthranilate) and some other (3-arylcarbonyl)-alanines. Humans express one kynureninase enzyme that is encoded by the ''KYNU'' gene located on chromosome 2. KYNU is part of the pathway for the catabolism of tryptophan, Trp and the biosynthesis of Nicotinamide adenine dinucleotide, NAD cofactor (biochemistry), cofactors from tryptophan (Trp). Kynureninase catalyzes the following reaction: : L-kynurenine + H2O ↔ anthranilic acid, anthranilate + L-alanine Structure Kynureninase belongs to the aminotransferase, class V, class V group of aspartate transaminase, aspartate aminotransferase superfamily of structurally homologous pyridoxal 5'-phosphate (pyridoxal phosphate, PLP) dependent enzymes. To date, two structures of human kynureninase have determin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenine
-Kynurenine is a metabolite of the amino acid -tryptophan used in the production of niacin. Kynurenine is synthesized by the enzyme tryptophan dioxygenase, which is made primarily but not exclusively in the liver, and indoleamine 2,3-dioxygenase, which is made in many tissues in response to immune activation. Kynurenine and its further breakdown products carry out diverse biological functions, including dilating blood vessels during inflammation and regulating the immune response. Some cancers increase kynurenine production, which increases tumor growth. Kynurenine protects the eye by absorbing UV light, especially in the UVA region (315–400 nm). Kynurenine is present in the lens and retina as one of multiple tryptophan derivatives produced in the eye, including 3-hydroxykynurenine, that together provide UV protection and aid in enhancing visual acuity. The use of kynurenine as a UV filter is consistent with its photostability and low photosensitization, owing to its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aminotransferase, Class V
Aminotransferase class-V is an evolutionary conserved protein domain. This domain is found in amino transferases, and other enzymes including cysteine desulphurase EC:4.4.1.-. Aminotransferases share certain mechanistic features with other pyridoxal- phosphate dependent enzymes, such as the covalent binding of the pyridoxal- phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped into subfamilies. This family is called class-V. Subfamilies *Phosphoserine aminotransferase *Cysteine desulfurase *Cysteine desulphurase related, unknown function *Cysteine desulphurases, SufS *Cysteine desulphurase related *2-aminoethylphosphonate—pyruvate transaminase Human proteins containing this domain AGXT; Kynureninase, KYNU; MOCOS; NFS1; PSAT1; SCLY; TLH6; References {{InterPro content, IPR000192 Protein domains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthranilic Acid
Anthranilic acid is an aromatic acid with the formula C6H4(NH2)(CO2H) and has a sweetish taste. The molecule consists of a benzene ring, ''ortho''-substituted with a carboxylic acid and an amine. As a result of containing both acidic and basic functional groups, the compound is amphoteric. Anthranilic acid is a white solid when pure, although commercial samples may appear yellow. The anion 6H4(NH2)(CO2)sup>−, obtained by the deprotonation of anthranilic acid, is called anthranilate. Anthranilic acid was once thought to be a vitamin and was referred to as vitamin L1 in that context, but it is now known to be non-essential in human nutrition. Structure Although not usually referred to as such, it is an amino acid. Solid anthranilic acid typically consists of both the amino-carboxylic acid and the zwitterionic ammonium carboxylate forms, and has a monoclinic crystal structure with space group P21. It is triboluminescent. Above , it converts to an orthorhombic form with spa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases. ''Nucleophilic'' describes the affinity of a nucleophile to bond with positively charged Atomic nucleus, atomic nuclei. Nucleophilicity, sometimes referred to as nucleophile strength, refers to a substance's nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as Alcohol (chemistry), alcohols and water are named solvolysis. Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge, and nucleophilic addition. Nucleophilicity is closely related to basicity. The difference between the two is, that basicity is a thermodynamic property (i.e. relates to an equilibrium state), but nucleop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schiff Base
In organic chemistry, a Schiff base (named after Hugo Schiff) is a compound with the general structure ( = alkyl or aryl, but not hydrogen). They can be considered a sub-class of imines, being either secondary ketimines or secondary aldimines depending on their structure. Anil refers to a common subset of Schiff bases: imines derived from anilines. The term can be synonymous with azomethine which refers specifically to secondary aldimines (i.e. where R' ≠ H). Synthesis Schiff bases can be synthesized from an aliphatic or aromatic amine and a carbonyl compound by nucleophilic addition forming a hemiaminal, followed by a dehydration to generate an imine. In a typical reaction, 4,4'-oxydianiline reacts with ''o''- vanillin: Schiff bases can also be synthesized via the Aza-Wittig reaction. Biochemistry Schiff bases have been investigated in relation to a wide range of contexts, including antimicrobial, antiviral and anticancer activity. They have also been con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tautomer
In chemistry, tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydrogen atom within the compound. The phenomenon of tautomerization is called tautomerism, also called desmotropism. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life. Care should be taken not to confuse tautomers with depictions of "contributing structures" in chemical resonance. Tautomers are distinct chemical species that can be distinguished by their differing atomic connectivities, molecular geometries, and physicochemical and spectroscopic properties, whereas resonance forms are merely alternative Lewis structure (valence bond theory) depictions of a single chemical species, whose true structure is a quantum superposition, essentially the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transamination
Transamination is a chemical reaction that transfers an amino group to a ketoacid to form new amino acids.This pathway is responsible for the deamination of most amino acids. This is one of the major degradation pathways which convert essential amino acids to non-essential amino acids (amino acids that can be synthesized de novo by the organism). Transamination in biochemistry is accomplished by enzymes called transaminases or aminotransferases. α-ketoglutarate acts as the predominant amino-group acceptor and produces glutamate as the new amino acid. :Amino acid, Aminoacid + α-ketoglutarate ↔ α-keto acid + Glutamic acid, glutamate Glutamate's amino group, in turn, is transferred to oxaloacetate in a second transamination reaction yielding aspartate. :Glutamic acid, Glutamate + oxaloacetate ↔ α-ketoglutarate + aspartate Mechanism of action Transamination catalyzed by aminotransferase occurs in two stages. In the first step, the α amino group of an amino acid is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridoxal Phosphate
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates. Role as a coenzyme PLP acts as a coenzyme in all transamination reactions, and in certain decarboxylation, deamination, and racemization reactions of amino acids. The aldehyde group of PLP forms a Schiff-base linkage (internal aldimine) with the ε-amino group of a specific lysine group of the aminotransferase enzyme. The α-amino group of the amino acid substrate displaces the ε-amino group of the active-site lysine residue in a process known as transaldimination. The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspartate Transaminase
Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase (GOT, SGOT), is a pyridoxal phosphate (PLP)-dependent transaminase enzyme () that was first described by Arthur Karmen and colleagues in 1954. AST catalyzes the reversible transfer of an α-amino group between aspartate and glutamate and, as such, is an important enzyme in amino acid metabolism. AST is found in the liver, heart, skeletal muscle, kidneys, brain, red blood cells and gall bladder. Serum AST level, serum ALT (alanine transaminase) level, and their ratio (AST/ALT ratio) are commonly measured clinically as biomarkers for liver health. The tests are part of blood test, blood panels. The biological half-life, half-life of total AST in the circulation approximates 17 hours and, on average, 87 hours for ''mitochondrial'' AST. Aminotransferase is cleared by Liver sinusoidal endothelial cell, sinusoidal cells in the liver. Function Aspartate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridoxal-phosphate
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates. Role as a coenzyme PLP acts as a coenzyme in all transamination reactions, and in certain decarboxylation, deamination, and racemization reactions of amino acids. The aldehyde group of PLP forms a Schiff-base linkage (internal aldimine) with the ε-amino group of a specific lysine group of the aminotransferase enzyme. The α-amino group of the amino acid substrate displaces the ε-amino group of the active-site lysine residue in a process known as transaldimination. The result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that assist in biochemical transformations. The rates at which these happen are characterized in an area of study called enzyme kinetics. Cofactors typically differ from ligands in that they often derive their function by remaining bound. Cofactors can be classified into two types: inorganic ions and complex organic molecules called coenzymes. Coenzymes are mostly derived from vitamins and other organic essential nutrients in small amounts. (Some scientists limit the use of the term "cofactor" for inorganic substances; both types are included here.) Coenzymes are further divided into two types. The first is called a " prosthetic group", which consists of a coenzyme that is tightly (or even covalently and, therefore, permanently) bound to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
