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Updated: Dec 22, 2025

Neutron Crystallography Data Collection and Processing for Modelling Hydrogen Atoms in Protein Structures
Published on: December 1, 2020
Neutron crystallography of copper amine oxidase reveals keto/enolate interconversion of the quinone cofactor and
Takeshi Murakawa1, Kazuo Kurihara2, Mitsuo Shoji3,4
1Department of Biochemistry, Osaka Medical College, 569-8686 Takatsuki, Osaka, Japan; murakawa@osaka-med.ac.jp tokajima@sanken.osaka-u.ac.jp.
Abstract:
Recent advances in neutron crystallographic studies have provided structural bases for quantum behaviors of protons observed in enzymatic reactions. Thus, we resolved the neutron crystal structure of a bacterial copper (Cu) amine oxidase (CAO), which contains a prosthetic Cu ion and a protein-derived redox cofactor, topa quinone (TPQ). We solved hitherto unknown structures of the active site, including a keto/enolate equilibrium of the cofactor with a nonplanar quinone ring, unusual proton sharing between the cofactor and the catalytic base, and metal-induced deprotonation of a histidine residue that coordinates to the Cu. Our findings show a refined active-site structure that gives detailed information on the protonation state of dissociable groups, such as the quinone cofactor, which are critical for catalytic reactions.
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