Kynurenine—oxoglutarate transaminase

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kynurenine-oxoglutarate transaminase
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Kynurenine aminotransferase-I homodimer, Human
Identifiers
EC no. 2.6.1.7
CAS no. 9030-38-0
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In enzymology, a kynurenine-oxoglutarate transaminase (EC 2.6.1.7) is an enzyme that catalyzes the chemical reaction

Contents

L-kynurenine + 2-oxoglutarate 4-(2-aminophenyl)-2,4-dioxobutanoate + L-glutamate

Thus, the two substrates of this enzyme are L-kynurenine and 2-oxoglutarate, whereas its two products are 4-(2-aminophenyl)-2,4-dioxobutanoate and L-glutamate. The former product is an unstable α-oxo acid that quickly undergoes intramolecular cyclization to form kynurenic acid. [1]

This enzyme belongs to the family of transferases, to be specific, the transaminases, that transfer nitrogenous groups. The systematic name of this enzyme class is L-kynurenine:2-oxoglutarate aminotransferase. Other names in common use include kynurenine transaminase (cyclizing), kynurenine 2-oxoglutarate transaminase, kynurenine aminotransferase, and L-kynurenine aminotransferase. This enzyme participates in tryptophan metabolism. It employs one cofactor, pyridoxal phosphate.

KYAT1, AADAT (aka KYAT2), and KYAT3 are examples of enzymes of this class. GOT2 (aka KYAT4) is also believed to catalyze the above reaction. [2]

Structural studies

As of early 2009, 18 structures have been solved for this class of enzymes, with PDB accession codes 1X0M, 1YIY, 1YIZ, 1W7L, 1W7M, 1W7N, 3E2F, 3E2Y, 3E2Z, 2ZJG, 2YGZ, 2Z61, 2R5C, 2R2N, 2R5E, 3B46, 3DC1, and 2QLN.

Related Research Articles

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Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase, 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 level, and their ratio are commonly measured clinically as biomarkers for liver health. The tests are part of blood panels.

<span class="mw-page-title-main">Kynurenic acid</span> Chemical compound

Kynurenic acid is a product of the normal metabolism of amino acid L-tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an antagonist at excitatory amino acid receptors. Because of this activity, it may influence important neurophysiological and neuropathological processes. As a result, kynurenic acid has been considered for use in therapy in certain neurobiological disorders. Conversely, increased levels of kynurenic acid have also been linked to certain pathological conditions.

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<span class="mw-page-title-main">GOT2</span> Mitochondrial enzyme involved in amino acid metabolism

Aspartate aminotransferase, mitochondrial is an enzyme that in humans is encoded by the GOT2 gene. Glutamic-oxaloacetic transaminase is a pyridoxal phosphate-dependent enzyme which exists in cytoplasmic and inner-membrane mitochondrial forms, GOT1 and GOT2, respectively. GOT plays a role in amino acid metabolism and the urea and Kreb's cycle. Also, GOT2 is a major participant in the malate-aspartate shuttle, which is a passage from the cytosol to the mitochondria. The two enzymes are homodimeric and show close homology. GOT2 has been seen to have a role in cell proliferation, especially in terms of tumor growth.

<span class="mw-page-title-main">KYAT1</span> Protein-coding gene in the species Homo sapiens

Kynurenine—oxoglutarate transaminase 1 is an enzyme that in humans is encoded by the CCBL1 gene. It is one of the Kynurenine—oxoglutarate transaminases.

Phosphoserine transaminase is an enzyme with systematic name O-phospho-L-serine:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction

UDP-4-amino-4-deoxy-L-arabinose aminotransferase is an enzyme with systematic name UDP-4-amino-4-deoxy-beta-L-arabinose:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction

DTDP-3-amino-3,6-dideoxy-alpha-D-galactopyranose transaminase is an enzyme with systematic name dTDP-3-amino-3,6-dideoxy-alpha-D-galactopyranose:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction

UDP-4-amino-4,6-dideoxy-N-acetyl-beta-L-altrosamine transaminase is an enzyme with systematic name UDP-4-amino-4,6-dideoxy-N-acetyl-beta-L-altrosamine:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">AADAT</span> Mammalian protein found in Homo sapiens

Kynurenine/alpha-aminoadipate aminotransferase, mitochondrial, also known as alpha-aminoadipate aminotransferase and kynurenine aminotransferase 2, is a mitochondrial enzyme that in humans is encoded by the AADAT gene. It converts alpha-aminoadipate to alpha-ketoadipate. It is also one of the Kynurenine—oxoglutarate transaminases.

References

  1. Han Q, Cai T, Tagle DA, Robinson H, Li J (August 2008). "Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II". Bioscience Reports. 28 (4): 205–15. doi:10.1042/BSR20080085. PMC   2559858 . PMID   18620547.
  2. Guidetti P, Amori L, Sapko MT, Okuno E, Schwarcz R (July 2007). "Mitochondrial aspartate aminotransferase: a third kynurenate-producing enzyme in the mammalian brain". Journal of Neurochemistry. 102 (1): 103–11. doi:10.1111/j.1471-4159.2007.04556.x. PMID   17442055. S2CID   20413002.

Further reading