In vitro inhibition of yeast valyl-tRNA synthetase by the valine homologue of ochratoxin A

Abstract

An analogue of valine in which valine is coupled by its amino group to a chlorinated dihydroisocoumarin moiety inhibits competitively the tRNA^Val charging with valine catalyzed by pure yeast valyl-tRNA synthetase. The inhibition constant is much lower for the ATPaiPP_i exchange reaction than for the tRNA charging one, indicating different rate-determining steps in the two reactions.