Synthesis of a novel chitosan-based Ce(IV) complex with proteolytic activity in vitro toward edible biological proteins

• Chitosan–cyclenCe(IV) complexes were synthesized as artificial metalloproteinase.
• The high hydrolytic efficiency toward myoglobinand ovalbumin was investigated.
• The cleavage sites for hydrolyzing Mb were embodied inAsp, Pheand Tyr.
• Excision enzyme activity of complexes for proteolysis was confirmed.
• High metal stabilityof complexesensuredsafe application in food production.

The occurrence of enzymatic activities is attributed to proper spatial organization of functional groups from first principles. A novel chitosan-based Ce(IV) complex (CC[Ce(IV)]), an artificial metalloproteinase, was synthesized by attaching cyclen, Ce(IV), and chlorophyll–Cu(II) to a chitosan-based matrix. The enzymatic hydrolytic efficiency (HE) and the procedure of catalyzing myoglobin (Mb) by CC[Ce(IV)] in vitro were investigated using spectrophotometry, electrophoresis, and liquid chromatography. The results showed that the HE of Mb was up to 60% at 60 °C within 24 h, displaying a catalytic proficiency. The pseudo-first-order kinetic constant (kobs) for CC[Ce(IV)] treatment within 24 h was 3.85 × 10−2 h−1, higher than that for α-chymotrypsin treatment, which was 2.63 × 10−2 h−1. Moreover, the peptide bond derived from Asp-Phe/Phe-Asp in Mb could be specifically cleaved by CC[Ce(IV)], which could simulate the functionality of α-chymotrypsin. This work provides an experimental basis for potential utilization of the chitosan-based Ce(IV) complexes in the food industry.