Abstract: In order to investigate the application potential of prolyl endopeptidase (PEP) in the enzymatic preparation of bone collagen peptides, the amino acid sequence characteristics of bovine bone collagen (BBC), porcine bone collagen (PBC) and chicken bone collagen (CBC) were comparatively analyzed, and their potential enzymatic cleavage sites and theoretical hydrolysis degrees were predicted. Collagen hydrolyzed by PEP at 55 ℃ and pH 8.0 was characterized by hydrolysis degree, molecular mass distributionand scanning electron microscopy (SEM). Infrared spectroscopy, X-ray diffraction (XRD) and circular dichroism (CD) spectroscopy were used to explore the structural changes of collagen during enzymatic digestion. The results showed that PEP could hydrolyze the three collagens. The hydrolysis degree of PBC was the highest (51.35%), followed by those of BBC (22.81%) and CBC (29.81%). The molecular masses of the three collagen hydrolysates were mostly distributed below 500 Da. Spectroscopic analysis showed that PEP destroyed the triple helix structure of collagen, and then degraded it. Therefore, PEP can efficiently enzymatically hydrolyze collagen into small molecule peptides, which provides a basis for the enzymatic preparation of functional collagen-derived peptides.

Key words: prolyl endopeptidase; collagen; enzymatic hydrolysis; high-value utilization