Decarboxylation of S-adenosyl-L-methionine in vitamin B6 deficiency in rat liver.

The effect of a prolonged diet deficient in B6-vitamin on the activity of adenosylmethionine decarboxylase from rat liver was investigated. In contrast to an earlier report, 12 adenosylmethionine decarboxylase activity was not found to be decreased under these restricted nutritional conditions. Moreover, the addition of pyridoxal phosphate into the standard incubation mixture did not stimulate the activity of adenosylmethionine decarboxylase from the livers of the rats fed the B6-vitamin deficient diet. It is suggested that the contradictory results of Sturman and Kremzner12 might be based on an artificial liberation of carbon dioxide from S-adenosyl-L-methionine in the presence of pyridoxal phosphate. The results of this communication do not support the view that pyridoxal phosphate acts as the prosthetic group of rat liver adenosylmethionine decarboxylase.