title: Chorionic peptidase inactivates GnRH as a post-proline peptidase.
abstract: Recently, we have described a chorionic peptidase (C-ase-1) which inactivates gonadotropin releasing hormone (GnRH), oxytocin, angiotensin II and thyrotropin releasing hormone. Since all these hormones contain a proline residue, we proposed that C-ase-1 may act as a post-proline peptidase. Using HPLC and amino acid analyses, we have defined the products which resulted from enzymatic inactivation of GnRH by C-ase-1. The N-terminal nonapeptide of GnRH was isolated by HPLC and confirmed by amino acid composition analyses. Thus, it was demonstrated that C-ase-1 acts as a post-proline peptidase when inactivating GnRH, yielding the nonapeptide, i.e., des-Gly10-NH2-GnRH, and Gly-NH2. The levels of intrauterine GnRH, angiotensin II, oxytocin and thyrotropin releasing hormone may be affected and integrated by this enzyme. Thus, C-ase-1 may play an important role in the regulation of the paracrine and endocrine function during pregnancy.
authors.affiliation: Department of Obstetrics & Gynecology, University of Texas Health Science Center, San Antonio 78284.
authors.forename: I S
authors.initials: IS
authors.lastname: Kang
authors.forename: T M
authors.initials: TM
authors.lastname: Siler-Khodr
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D010450:Endopeptidases / Q000494:pharmacology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D011863:Radioimmunoassay
chemical_list: D000596:Amino Acids; D007987:Gonadotropin-Releasing Hormone; D010450:Endopeptidases; C060922:chorionic peptidase I