PDBsum entry 4zm7

Hydrolase

PDB id: 4zm7

Contents

Protein chain

180 a.a.

Waters ×469

References listed in PDB file

Key reference

• Title: &Quot;newton'S cradle" proton relay with amide-Imidic acid tautomerization in inverting cellulase visualized by neutron crystallography.
• Authors: A.Nakamura, T.Ishida, K.Kusaka, T.Yamada, S.Fushinobu, I.Tanaka, S.Kaneko, K.Ohta, H.Tanaka, K.Inaka, Y.Higuchi, N.Niimura, M.Samejima, K.Igarashi.
• Ref.: Sci Adv, 2015, 1, e1500263. [DOI no: 10.1126/sciadv.1500263]
• PubMed id: 26601228

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 molecular dynamics simulations of not only cellulases but also general enzyme catalysis, and it may be necessary to reconsider our interpretation of many enzymatic reactions.