Hamre Anne Grethe, Eide Kristine B, Wold Hanne H, Sørlie Morten
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, N-1432 Ås, Norway.
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, N-1432 Ås, Norway.
Carbohydr Res. 2015 Apr 30;407:166-9. doi: 10.1016/j.carres.2015.02.010. Epub 2015 Mar 2.
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 k(cat) (k(cat)(app)) values on a β-chitin substrate. k(cat)(app) 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 k(cat)(app) 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)).
几十年来，人们一直认为纤维素和几丁质等难降解多糖的酶促转化完全依赖水解酶的协同作用，但最近的研究表明，裂解多糖单加氧酶（LPMO）是这一过程的重要贡献者。在此，我们通过测定β-几丁质底物上的表观催化常数（k(cat)(app)）值，研究了一种LPMO（CBP21）对粘质沙雷氏菌几丁质分解机制中的水解酶（ChiA、ChiB和ChiC）的初始速率增强作用。对于外切活性的ChiA和ChiB，k(cat)(app)值分别测定为1.7±0.1 s(-1)和1.7±0.1 s(-1)，对于内切活性的ChiC，k(cat)(app)值为1.2±0.1 s(-1)。添加CBP21提高了ChiA和ChiB的k(cat)(app)值，分别为11.1±1.5 s(-1)和13.9±1.4 s(-1)，而对ChiC没有影响（0.9±0.1 s(-1)）。
