"Newton's cradle" proton relay with amide-imidic acid tautomerization in inverting cellulase visualized by neutron crystallography.

ABSTRACT: Hydrolysis of carbohydrates is a major bioreaction in nature, catalyzed by glycoside hydrolases (GHs). We used neutron diffraction and high-resolution x-ray diffraction analyses to investigate the hydrogen bond network in inverting cellulase PcCel45A, which is an endoglucanase belonging to subfamily C of GH family 45, isolated from the basidiomycete Phanerochaete chrysosporium. Examination of the enzyme and enzyme-ligand structures indicates a key role of multiple tautomerizations of asparagine residues and peptide bonds, which are finally connected to the other catalytic residue via typical side-chain hydrogen bonds, in forming the "Newton's cradle"-like proton relay pathway of the catalytic cycle. Amide-imidic acid tautomerization of asparagine has not been taken into account in recent m

SUBMITTER: Nakamura A 

PROVIDER: S-EPMC4643802 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature