Binding of glycolytic enzymes to cardiac sarcolemmal and sarcoplasmic reticular membranes.

Abstract Glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase activities were associated with a particulate fraction in a cardiac homogenate preparation. NaCl treatment displaced these activities from the particulate fraction. These membrane-associated glycolytic enzymes were gradually lost during the rigorous isolation procedures needed to purify sarcolemmal and sarcoplasmic reticular vesicles. However, exogenously added enzymes did bind to these purified membranes in relatively large quantities (glyceraldehyde-phosphate dehydrogenase: 1.14 mg of enzyme/mg of sarcolemma, 0.30 mg of enzyme/mg of sarcoplasmic reticulum; phosphoglycerate kinase: 1.02 mg of enzyme/mg of sarcolemma, 0.12 mg of enzyme/mg of sarcoplasmic reticulum), which suggests a nonspecific type of binding interaction. Approximately 50% of the glyceraldehyde-phosphate dehydrogenase and 90% of the phosphoglycerate kinase were inactivated upon binding. NaCl removed the enzyme from the membranes in a concentration-dependent manner similar to its effects in the particulate fraction. Dimethonium (5 mM), an organic divalent cation which screens membrane-surface charge, removed greater than 90% glyceraldehyde-phosphate dehydrogenase from the sarcolemmal membrane. These results, and those with NaCl, suggest that the binding of the enzyme to the membrane is charge-related. Phospholipids extracted from the sarcolemmal membrane were capable of binding and inactivating both glycolytic enzymes. Purified anionic phospholipids were more potent at binding and inactivating both enzymes than were neutral phospholipids. These data show that glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase can bind to sarcolemmal and sarcoplasmic reticular membranes. This binding is reversible, charge-dependent, and inhibitory. This binding is likely to involve anionic membrane phospholipids.