[A proteolytic enzyme bound to the aspartate transaminase of swine heart cytosol].

Purified preparations of aspartate transaminase from pig heart cytosol contain a tightly bound proteolytic enzyme (approximately 2, 5%). The enzyme was separated from aspartate transaminase by gel-filtration on Sephadex G-100 in the presence of sodium dodecyl sulfate and by affinity chromatography on the column with Sepharose, containing covalently bound denaturated aspartate transaminase. Protease has a pH optimum of 9.0 and molecular weight of about 23.000-25.000. The proteolysis rates of different subforms of aspartate transaminase depend on their denaturation lability. A more stable choloenzyme is split at a slower rate than the apoenzyme. An enriched preparation of protease was also shown to split glutamate decarboxylase from E. coli and had no effect on cysteinlyase from hen egg, as well as on lactate dehydrogenase and albumin.