title: A novel SH-type carboxypeptidase in the inner membrane of rat-liver mitochondria.
abstract: A carboxypeptidase from rat liver mitochondria was partially purified by discontinuous sucrose gradient centrifugation, washes with NaCl/KBr/Tris buffer, and solubilization with 2 M NaCl in the presence of soybean trypsin inhibitor bound to CM-cellulose. By means of dodecylsulfate/polyacrylamide gel electrophoresis a molecular weight of 34,500 was determined; a value of 38,000 was estimated by Sephadex G-100 gel filtration. The carboxypeptidase was completely inhibited by 3 mM Hg2+. In the presence of 3 mM Cu2+ 50% of the catalytic activity was inhibited. Among several peptides tested Cbz-Ala-Phe, Cbz-Leu-Phe, Cbz-Phe-Leu, and Cbz-Phe-Phe, were good substrates. The enzyme activity exhibited a pH optimum of around 9 with Cbz-Ala-Phe as a substrate. After submitochondrial fractionation it was found that the carboxypeptidase is located in the inner mitochondrial membrane.
mesh_terms: D000818:Animals; D002268:Carboxypeptidases / Q000302:isolation & purification / Q000378:metabolism*; D002413:Cations, Divalent; D004492:Edetic Acid / Q000494:pharmacology; D007425:Intracellular Membranes / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D051381:Rats; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D004492:Edetic Acid; D002268:Carboxypeptidases