| Abstract: | Hepatic cystathionase activity, but not methionine adenosyl-transterase and cystathionine synthetase, was markedly decreased in weanling female rats fed a vitamin B6-deficient diet, compared to that of the control animals fed ad libitum or pair-fed. The depressed enzyme activity was restored rapidly to normal by administering pyridoxine to the deficient rats. Excess pyridoxal phosphate added to enzyme reaction mixtures stimulated cystathionase in liver extracts from both control and deficient animals, but it did not raise activity of deficients to normal level. The data indicate that the amount of apocystathionase in rat liver is regulated by the availability of its coenzyme vitamin. |
