title: Two peptidases that convert 125I-Lys-Arg-(Met)enkephalin and 125I-(Met)enkephalin-Arg6, respectively, to 125I-(Met)enkephalin in bovine adrenal medullary chromaffin granules.
abstract: Two peptidases which convert 125I-Lys-Arg-ME and 125I-ME-Arg6, respectively, to 125I-ME, have been identified and characterized in bovine adrenomedullary chromaffin granules. The former is referred to as a secretory granule peptidase (SGP) and the latter as a carboxypeptidase B-like enzyme (CPB-like) [7] which is here further characterized. SGP cleaved 125I-Lys-Arg-ME to produce only 125I-ME and was localized in chromaffin granules which contained Co2+-stimulated CPB-like activity, ME, and catecholamines. Both the SGP and the CPB-like enzymes appear to be thiol-metalloproteases. While the CPB-like enzyme seems likely to be involved in processing the enkephalin precursors [7], SGP may function as a trypsin-like or aminopeptidase enzyme in secretory granules.
mesh_terms: D000818:Animals; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism*; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002614:Chelating Agents / Q000494:pharmacology; D002837:Chromaffin Granules / Q000201:enzymology*; D002838:Chromaffin System / Q000201:enzymology*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000378:metabolism*; D008247:Lysosomes / Q000201:enzymology; D010447:Peptide Hydrolases / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D011480:Protease Inhibitors; D013439:Sulfhydryl Reagents; D004744:Enkephalin, Methionine; C028719:enkephalin-Met, Arg(6)-; C042229:enkephalin-Met, Lys(6)-Arg(7)-; D002268:Carboxypeptidases; D010447:Peptide Hydrolases; D043424:Carboxypeptidase B