TY  - JOUR
AU  - Li, Zhihong
AU  - Zhang, Xiaoshuai
AU  - Wang, Qingqing
AU  - Li, Chunran
AU  - Zhang, Nianying
AU  - Zhang, Xinkai
AU  - Xu, Birui
AU  - Ma, Baoliang
AU  - Schrader, Tobias E.
AU  - Coates, Leighton
AU  - Kovalevsky, Andrey
AU  - Huang, Yandong
AU  - Wan, Qun
TI  - Understanding the pH-Dependent Reaction Mechanism of a Glycoside Hydrolase Using High-Resolution X-ray and Neutron Crystallographyülcih
JO  - ACS catalysis
VL  - 8
IS  - 9
SN  - 2155-5435
CY  - Washington, DC
PB  - ACS
M1  - FZJ-2019-00783
SP  - 8058 - 8069
PY  - 2018
AB  - Glycoside hydrolases (GHs) commonly use the retaining or inverting mechanisms to hydrolyze carbohydrates, and the rates of catalysis are usually pH dependent. Deeper understanding of these pH-dependent reaction mechanisms is of great importance for protein engineering and drug design. We used high-resolution X-ray crystallography to analyze the sugar ring configurations of an oligosaccharide ligand during hydrolysis for the family 11 GH, and the results support the 1S3 → 4H3 → 4C1 conformational itinerary. These results indicate that sugar ring flexibility may help to distort and break the glycosidic bond. Constant pH molecular dynamics simulations and neutron crystallography demonstrate that the catalytic glutamate residue (E177) has alternate conformational changes to transfer a proton to cleave the glycosidic bond. Furthermore, a neutron crystallography analysis shows that the H-bond length between E177 and its nearby tyrosine residue (Y88) is shortened when the pH increases, preventing E177 from rotating downward and obtaining a proton from the solvent for catalysis. This result indicates that the H-bond length variation may play a key role in the pH-dependent reaction mechanism. In summary, our results demonstrate that both sugar ring flexibility and protein dynamics are important in the pH-dependent reaction mechanism and may help to engineer GHs with different pH optima.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000444364800034
DO  - DOI:10.1021/acscatal.8b01472
UR  - https://juser.fz-juelich.de/record/859977
ER  -