Mammalian Histidine Ammonia Lyase

Abstract

Abstract Histidine-ammonia lyase (EC 4.3.1.3) from rat liver became inactivated and incorporated radioactivity upon incubation with 14C-nitromethane. Degradation of the 14C-protein yielded the same products that appear after 14C-nitromethane inactivation and degradation of the bacterial enzyme. Therefore, the two enzymes must possess an identical, or at least very similar electrophilic center at the active site. Injection of nitromethane into adult mice caused the inactivation of liver histidase. If the effect of nitromethane in vivo is specific, it will provide a model for the human genetic disorder, histidinemia.