Tryptophan Synthetase Activity in Pea Seedling Extracts.

Extracts of several microorganisms have been shown to possess tryptophan synthetase activity (2, 5, 6, 8, 9), i.e., such preparations, when incubated in buffer in the presence of indole, serine, and pyridoxal phosphate, catalyze a condensation of indole and serine with the concomitant production of an equivalent amount of tryptophan. Animals, which have a dietary requirement for tryptophan, appear to lack the enzyme, while the one study conducted with higher plant materials has yielded somewhat equivocal results (3). In this work, we present evidence for the existence of tryptophan synthetase activity in pea seedling extracts, and describe various characteristics of the enzyme system.