The effect of spermine on the interaction of AMP deaminase with threonine dehydratase activity in yeast

Evidence suggesting that AMP deaminase (EC 3.5.4.6) is responsible for the stimulation of threonine dehydratase (EC 4.2.1.16) activity in situ is presented using yeast cells which have been rendered permeable. The addition of polyamine, an activator of AMP deaminase, resulted in the increase in ammonia concentration, which can stimulate the activity of yeast threonine dehydratase. Polyamine may regulate the synthesis of isoleucine and valine, and of the intermediates of citric acid cycle through the activation of AMP deaminase-threonine dehydratase system as a ‘cascade system’ in yeast.