Reaction: (1) L-kynurenine + glyoxylate = kynurenate + glycine + H2O (overall reaction)
(1a) L-kynurenine + glyoxylate = 4-(2-aminophenyl)-2,4-dioxobutanoate + glycine
(1b) 4-(2-aminophenyl)-2,4-dioxobutanoate = kynurenate + H2O (spontaneous)
(2) 3-hydroxy-L-kynurenine + glyoxylate = xanthurenate + glycine + H2O (overall reaction)
(2a) 3-hydroxy-L-kynurenine + glyoxylate = 4-(2-amino-3-hydroxyphenyl)-2,4-dioxobutanoate + glycine
(2b) 4-(2-amino-3-hydroxyphenyl)-2,4-dioxobutanoate = xanthurenate + H2O (spontaneous)
For diagram click here (mechanism).
Glossary: kynurenine = 2-amino-4-(2-aminophenyl)-4-oxobutanoic acid = 3-anthraniloylalanine
kynurenate = 4-hydroxyquinoline-2-carboxylate
xanthurenate = 4,8-dihydroxyquinoline-2-carboxylate
Other name(s): kynurenine-glyoxylate aminotransferase
Systematic name: L-kynurenine:glyoxylate aminotransferase (cyclizing)
Comments: This enzyme, characterized from animals, belongs to a family of aminotransferases some members of which can use other amino acceptors ( cf . EC 2.6.1.7, kynurenine—oxoglutarate transaminase). The products, 4-(2-aminophenyl)-2,4-dioxobutanoate and 4-(2-amino-3-hydroxyphenyl)-2,4-dioxobutanoate, are converted to kynurenate and xanthurenate, respectively, by spontaneous reactions.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 74506-33-5
References:
1. Harada, I., Noguchi, T. and Kido, R. Purification and characterization of aromatic-amino-acid-glyoxylate aminotransferase from monkey and rat liver. Hoppe-Seylers Z. Physiol. Chem. 359 (1978) 481–488. [PMID: 25837] 2. Harada, I. [Glucagen inducible kynurenine aminotransferase.] Wakayama Igaku 31 (1980) 61–68. (in Japanese) 3. Han, Q., Fang, J. and Li, J. 3-Hydroxykynurenine transaminase identity with alanine glyoxylate transaminase. A probable detoxification protein in Aedes aegypti . J. Biol. Chem. 277 (2002) 15781–15787. [PMID: 11880382] 4. Rossi, F., Lombardo, F., Paglino, A., Cassani, C., Miglio, G., Arca, B. and Rizzi, M. Identification and biochemical characterization of the Anopheles gambiae 3-hydroxykynurenine transaminase. FEBS J. 272 (2005) 5653–5662. [PMID: 16262702]