Chorionic peptidase inactivates GnRH as a post-proline peptidase.

Area of Science:

• Biochemistry
• Endocrinology
• Reproductive Biology

Background:

• A novel enzyme, chorionic peptidase (C-ase-1), has been identified.
• C-ase-1 inactivates several peptide hormones including gonadotropin-releasing hormone (GnRH), oxytocin, angiotensin II, and thyrotropin-releasing hormone.
• The presence of a proline residue in these substrates suggests C-ase-1 may function as a post-proline peptidase.

Purpose of the Study:

• To elucidate the enzymatic mechanism of C-ase-1 in the inactivation of GnRH.
• To characterize the specific products generated by C-ase-1 activity on GnRH.
• To investigate the potential role of C-ase-1 in regulating intrauterine hormone levels and reproductive functions.

Main Methods:

• High-Performance Liquid Chromatography (HPLC) for product isolation.
• Amino acid analysis for product confirmation.
• Enzymatic assays to study hormone inactivation.

Main Results:

• C-ase-1 was confirmed to act as a post-proline peptidase on GnRH.
• The inactivation of GnRH by C-ase-1 yielded the N-terminal nonapeptide (des-Gly10-NH2-GnRH) and Gly-NH2.
• HPLC and amino acid analyses successfully isolated and confirmed the resulting nonapeptide.

Conclusions:

• C-ase-1 functions as a post-proline peptidase, specifically cleaving after proline residues in peptide substrates.
• The enzyme's activity on GnRH produces des-Gly10-NH2-GnRH and Gly-NH2.
• C-ase-1 may play a significant role in regulating paracrine and endocrine functions during pregnancy by modulating hormone levels.