Effect of group specific reagents on the Mg2 +/- dependent activity of purified Micrococcus lysodeikticus ATPase

A series of group specific reagents has been examined for their ability to inactivate Micrococcus lysodeikticus adenosine triphosphatase assayed with Mg2+ as activating divalent cation. The enzyme activity was not inhibited by sulphydryl, carboxyl, histidine, arginine and methionine specific reagents at inhibitor concentrations below 2 mM. However, the ATPase was inactivated by its chemical reaction with either one molecule of trinitrobenzenesulfonic acid or tetranitromethane, or two to four molecules of N-bromosuccinimide. These results suggest that at least one amino group, one tyrosine and two to four tryptophans are involved in the Mg2+-dependent binding or hydrolysis of ATP.