Limited proteolysis of bovine muscle and heart lactate dehydrogenase is inhibited by phospholipid liposome interaction.

Limited proteolysis of phospholipid complexes of heart and muscle bovine lactate dehydrogenase by trypsin and chymotrypsin has been studied under nondenaturing condition at pH 7.5. Chymotrypsin cleaves the polypeptide chain of heart and muscle lactate dehydrogenase into two principal fragments and LDH subunits were protected by lipids towards the proteinase attack. Enzymatic activity of heart and muscle lactate dehydrogenase was abolished by limited proteolytic cleavage. In complexes, both isoenzymes were protected against proteinases attack by lipids.