Effects of steroid conjugates on availability of pyridoxal phosphate for kynureninase and kynurenine aminotransferase activity

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Abstract
Earlier studies of the effects of estrogen conjugates on the binding of pyridoxal phosphate to kynurenine aminotransferase are reviewed, and their possible relation to the effects of estrogens on the enzymes of tryptophan metabolism is discussed. A sex difference in rat liver kynureninase levels that is similar to one reported earlier for renal kynurenine aminotransferase is described. Although estrogen treatment of males depressed the aminotransferase levels to those typical of females, estrogen treatment of females did not further depress these levels. Earlier studies have indicated that the kynurenine aminotransferase levels are responsive to dietary changes. Tryptophan supplementation of male rats, however, did not significantly change the levels.