A higher plant enzyme exhibiting broad acceptance of stereoisomers

Abstract

An arginase, purified from the leaf of the jack bean, Canavalia ensiformis, can effectively hydrolyze both L- and D-arginine. Arginases, examined from a number of other plant and animal sources, exhibit marked substrate stereospecificity and fail to catabolize D-arginine. In order to provide essential nitrogen, jack bean leaf arginase also catabolizes L-canavanine, an arginine analog that is a predominant nitrogen-storing metabolite of this legume. The ability of arginase to metabolize both stereoisomers of arginine may result from the requirement for this enzyme to exhibit limited substrate specificity in order to hydrolyze both arginine and canavanine.