NADP+-linked malic enzymes from pig heart mitochondria — Apparent selective inhibition of one enzyme form

NADP + -linked malic enzyme activity was fractionated from mitochondria using sonication, freeze-thawing, ammonium sulfate precipitation, and calcium phosphate gel elution. Three bands of activity could be shown on disc gel electrophoresis using a stain specific for the enzyme. An inhibitor extracted from the calcium phosphate elution fraction was partially effective against freshly prepared enzyme but not against enzyme preparations stored for five days. During the five days there was a drop in enzyme activity nearly equal to the amount of original inhibition observed, and one of the fractions was no longer demonstrable by gel electrophoresis.