The influence of Zn2+ ions on the tryptophan biosynthesis in plants

Abstract

Zn2+ ions slightly enhance at low concentrations (0.01 μg ml-1) the activity of tryptophan synthase obtained from the shoots of 14-day-old pea seedlings (Pisum sativum L.). On the contrary, high concentrations of Zn2+ (10 μg ml-l) exert an inhibitory effect. The direct Zn2+ activation of tryptophan synthase, establishedin vitro with a partially purified enzyme preparation, is relatively low and obviously is not decisive from the point of view of tryptophan biosynthesis of the enzyme and thus they are participating in thein vivo experiments.