Activation of enzymatic chitin degradation by a lytic polysaccharide monooxygenase

• LPMO greatly enhances initial enzymatic recalcitrant carbohydrate degradation.
• LPMO enhances exo-hydrolases initially.
• LPMO appears not to enhance endo-hydrolases initially.

For decades, the enzymatic conversion of recalcitrant polysaccharides such as cellulose and chitin was thought to solely rely on the synergistic action of hydrolytic enzymes, but recent work has shown that lytic polysaccharide monooxygenases (LPMOs) are important contributors to this process. Here, we have examined the initial rate enhancement an LPMO (CBP21) has on the hydrolytic enzymes (ChiA, ChiB, and ChiC) of the chitinolytic machinery of Serratia marcescens through determinations of apparent kcat (kcatapp) values on a β-chitin substrate. kcatapp values were determined to be 1.7±0.1 s−1 and 1.7±0.1 s−1 for the exo-active ChiA and ChiB, respectively and 1.2±0.1 s−1 for the endo-active ChiC. The addition of CBP21 boosted the kcatapp values of ChiA and ChiB giving values of 11.1±1.5 s−1 and 13.9±1.4 s−1, while there was no effect on ChiC (0.9±0.1 s−1).

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