Purification and characterization of the major aminopeptidase from human skeletal muscle.
The major aminopeptidase from human quadriceps muscle was purified (as judged by polyacrylamide-gel electrophoresis) by anion-exchange chromatography (two steps) and gel filtration (two steps). The enzyme showed maximum activity at pH 7.3, in the presence of 1 mM-2-mercaptoethanol and 0.5 mM-Ca2+ ions; activation of the enzyme occurred in the presence of several other bivalent cations. Inhibition of activity was obtained in the presence of metal-ion-chelating agents and inhibitors of aminopeptidases and thiol proteinases. The molecular weight of the enzyme was 102 000 (by gel filtration). The enzyme hydrolysed several amino acyl-7-amido-4-methylcoumarin derivatives; highest activity was obtained with alanyl-7-amido-4-methylcoumarin. The enzyme also degraded a series of dipeptides, alanine oligopeptides and some naturally occurring peptides. Of particular interest was the high activity of the enzyme towards the enkephalins.
D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002413:Cations, Divalent; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D009132:Muscles / Q000201:enzymology*; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism
D002413:Cations, Divalent; D010446:Peptide Fragments; D010455:Peptides; D000626:Aminopeptidases