Malate dehydrogenase: A higher molecular weight form produced by freeze-thaw treatment of pig heart supernatant enzyme

Abstract

Attempts to produce hybrids of pig heart supernatant and mitochondrial malate dehydrogenase with the use of guanidine hydrochloride, acid treatment, and freezethaw techniques have been unsuccessful. However, the freeze-thaw technique produced a catalytically active higher molecular weight form of supernatant malate dehydrogenase in the absence or presence of mitochondrial enzyme. The higher molecular weight of this artifact was established by gel filtration and gel electrophoresis criteria. The specific activity of the artifactual form of the enzyme appears to be close to that of native supernatant malate dehydrogenase.