KYNU is a PLP dependent enzyme that catalyses the cleavage of Kyn (Kynurenine) and 3hKyn (3-hydroxy-kynurenine) into Ant (Anthranilate) and 3hAnt (3-hydroxy-anthranilate), respectively. KYNU is involved in the biosynthesis of NAD cofactors from Trp through the Kyn pathway. Wikipedia does not yet have an article with this exact name. ... Ribbon diagram of the catalytically perfect enzyme TIM. Factor D enzyme crystal prevents the immune system from inappropriately running out of control. ... Tryptophan is an amino acid and essential in human nutrition. ...

Structure

Function

In KYNU reaction PLP facilitates C_β-C_γ 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_γ) of the tautomerized 3hKyn-PLP Schiff base. This is followed by C_β-C_γ bond cleavage to generate an acyl-enzyme intermediate together with a tautomerized Ala-PLP adduct. Hydrolysis of the acyl-enzyme then yields 3hAn.

The KYNU's reaction mechanism.

The color scheme is as follows: KYNU, PLP, substrate names, inorganic molecules, 3hAn's moiety, Ala's moiety