title: Characterization of a nonchymotrypsin-like endopeptidase from anterior pituitary that hydrolyzes luteining hormone-releasing hormone at the tyrosyl-glycine and histidyl-tryptophan bonds.
abstract: A neutral endopeptidase which degrades luteinizing hormone-releasing hormone (LH-RH, <GLu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-GLy-NH2) has been purified 900-fold from extracts of bovine anterior pituitary. This Ca2+-independent enzyme of 83 000 molecular weight (as estimated by gel filtration) cleaves LH-RH (KM = 180 microM) at the Tyr5-Gly6-His2-Trp3 bonds. Its activity is inhibited by the SH-reactive agents N-ethylmaleimide and p-(chloromercuri)benzoate but not by the OH-reactive agent diisopropyl fluorophosphate. Hydrolysis of the fluorogenic chymotrypsin substrate glutarkyl-Gly-Gly-Phe-beta-naphthylamide by this endopeptidase could not be detected. These properties differentiate the endopeptidase from chymotrypsin and from a glutaryl-Gly-Gly-Phe-beta-naphthylamide hydrolyzing activity of high molecular weight, which has been isolated from the same tissue and also hydrolyzes internal bonds of LH-RH.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D005998:Glycine; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006639:Histidine; D007531:Isoflurophate / Q000494:pharmacology; D007700:Kinetics; D010903:Pituitary Gland, Anterior / Q000201:enzymology*; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014364:Tryptophan; D014443:Tyrosine
chemical_list: D013439:Sulfhydryl Reagents; D007531:Isoflurophate; D007987:Gonadotropin-Releasing Hormone; D014443:Tyrosine; D006639:Histidine; D014364:Tryptophan; D010450:Endopeptidases; D002118:Calcium; D005998:Glycine