Taurine and kynureninase.

Abstract

Kynureninase is the most important enzyme in tryptophan metabolism. In the main pathway of tryptophan metabolism, kynureninase forms 3-OH-anthranilic acid from 3-OH-kynurenine. In this reaction vitamin B6 is a co-enzyme. An important relationship between -SH groups and liver kynureninase apoenzyme has been reported by Takeuchi8, 9 and Izuta1. We have experimented on kynureninase and S-involved compounds as follows: (i) Kynureninase activity was inhibited in vitamin B6-deficient rats and in streptozotocin (STZ)-induced diabetic rats; (ii) Following tryptophan administration, in rats given taurine or oysters (rich in taurine), the excretion of xanthurenic acid (an index of vitamin B6 deficiency) decreased compared with an excess methionine-administered group; and (iii) The active center of kynureninase apoenzyme (464 amino acid residues) is located near cysteine.KeywordsPyridoxal PhosphateTryptophan MetabolismXanthurenic AcidInhibit Dopa DecarboxylaseAcid Dietary EnrichmentThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.