Studies on 3-hydroxykynureninase from rat liver.
Kynureninase (L-kynurenine hydrolase E.C. 3.7.1.3.) was purified about 200 times from rat liver. The purified enzyme catalyzes the L-3-hydroxykynurenine leads to 3-hydroxyanthranilate reaction more favorably than the L-kynurenine leads to anthranilate reaction, with Km values of 1.67 x 10(-6) M for L-3-hydroxykynurenine and of 1.67 x 10(-4) M for L-kynurenine. Besides, this enzyme did not produce 5-hydroxyanthranilate from D,L-5-hydroxykynurenine. Therefore we think it is mainly a 3-hydroxykynureninase regulating the tryptophan degradation towards the formation of nicotinic acid necessary to NAD synthesis, rather than towards the accumulation of anthranilate.
D000818:Animals; D006867:Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D007737:Kynurenine / Q000031:analogs & derivatives; D008099:Liver / Q000201:enzymology*; D051381:Rats
D007737:Kynurenine; D006867:Hydrolases