Kynurenine-Transaminase, Kynureninase and the Increase of Xanthurenic Acid Excretion

Abstract

Kynurenine transaminase is present in both supernatant and mitocnondrial fractions, while kynureninase is detectable only in the supernatant solution. The vitamin B6-deficient rat induced by the administration of DL-penicillamine(20 mg/100 g. body weight) increases the urinary excretion of xanthurenic acid, markedly lowers the activities of mitochondrial kynurenine transaminase and kynureninase, but not sol. supernatant kynurenine transaminase activities. Increased xanthurenic acid excretion is explained that accumulated 3-hydroxy- kynurenine under Bg-deficiency is metabolized to xanthurenic acid but not to 3-hydroxyantnranilic acid.