Abstract: To investigate the potential of prolyl endopeptidase (PEP) in the enzymatic preparation of bone collagen peptides, bovine bone collagen (BBC), porcine bone collagen (PBC) and chicken bone collagen (CBC) were used as raw materials. The sequence characteristics of the three different collagen sources were compared and analyzed to predict the potential enzymatic sites and theoretical hydrolysis degrees of the different collagens based on the PEP substrate specificity analysis. Three different collagen sources were enzymatically treated with PEP at 55℃ and pH 8.0, and the enzymatic effects of PEP on different collagen were analyzed by scanning electron microscopy, apparent turbidity changes, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis; and confirmed by hydrolysis degree and molecular weight changes. Infrared spectroscopy, X-ray diffraction and circular dichroism were used to explore the structural changes of collagen during enzymatic digestion. The results showed that PEP had significant hydrolysis effect on three different sources of collagen. The hydrolysis degree of pig collagen was the highest at 51.35%, followed by bovine collagen at 22.81% and chicken collagen at 29.81%. The molecular weight of the three collagen proteinase hydrolysates mostly distributed below 500 Da. Spectroscopic analysis showed that PEP destroyed the triple helix structure of collagen, and then degraded collagen to achieve the effect of collagen peptide preparation. Conclusion: Prolyl endopeptidase can efficiently enzymolize collagen to prepare small molecule protein peptide, which provides the basis for the enzymatic preparation of functional collagen peptide.

Key words: Prolyl endopeptidase, Collagen, Enzymatic hydrolysis, High value utilization