Kynureninase

protein
Name = kynureninase
caption =


width =
HGNCid = 6469
Symbol = KYNU
AltSymbols =
EntrezGene = 8942
OMIM = 236800
RefSeq = NM_001032998
UniProt = Q16719
PDB =
ECnumber = 3.7.1.3
Chromosome = 2
Arm = q
Band = 22
LocusSupplementaryData = -2q23.3

Kynureninase or L-Kynurenine hydrolase (KYNU) (EC number|3.7.1.3) is a PLP dependent enzyme that catalyses the cleavage of Kyn into Ant. It can also act on 3hKyn (to produce 3hAnt) and some other (3-arylcarbonyl)-alanines.

KYNU is part of the pathways for the catabolism of Trp and the biosynthesis of NAD cofactors from Trp.

tructure

Function

In KYNU reaction, PLP facilitates C-C bond cleavage. The reaction follows the same steps as the transamination reaction but does not hydrolyze the tautomerized Schiff base. The proposed reaction mechanism involves an attack of an enzyme nucleophile on the carbonyl carbon (C) of the tautomerized 3hKyn-PLP Schiff base. This is followed by C-C bond cleavage to generate an acyl-enzyme intermediate together with a tautomerized Ala-PLP adduct. Hydrolysis of the acyl-enzyme then yields 3hAnt.