Biochemical characteristics and substrate degradation pattern of a recombinant chondroitinase B from Pseudopedobacter saltans heterologously in Escherichia coli

Chondroitinase B (CSase B) is a kind of enzyme that specifically cleaves dermatan sulfates (DS) domain from the glycosaminoglycans (GAGs) chains, and plays important roles in functional oligosaccharide preparation and GAGs structural and functional studies. However, to date, only two wild-type DS-degrading enzymes with high specificity have been reported, one is the DS-degrading enzyme cslB from Pedobacter heparinus , and the other is chondroitin B lyase, named Ps ChonB, produced by Pedobacter schmidaeae. In this study, we identified a PL6-family gene from Pseudopedobacter saltans , named DLase, and heterologously expressed the recombinant enzyme in Escherichia coli (E. coli). DLase is an endo-type lyase with high specificity for DS domain and exhibits excellent enzymatic properties. Notably, the specific activity of DLase (911 U/mg) is substantially higher than that of cslB (84.6 U/mg) and Ps ChonB (395 U/mg). Furthermore, unlike cslB and Ps ChonB, DLase exhibits high activity over a broader range of temperatures and pH conditions, and also demonstrates superior thermostability. Additionally, this study is the first to determine the impact of other GAGs on CSase B enzyme activity. The enzyme will serve as valuable tools for studying the structure-activity relationship of DS and other GAGs.