Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10537294 | Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics | 2013 | 7 Pages |
Abstract
The protonation states and hydration structures of the α-thrombin-bivalirudin complex were studied by joint XN refinement of the single crystal X-ray and neutron diffraction data at resolutions of 1.6 and 2.8 Ã
, respectively. The atomic distances were estimated by carrying out X-ray crystallographic analysis at 1.25Â Ã
resolution. The complex represents a model of the enzyme-product (EP) complex of α-thrombin. The neutron scattering length maps around the active site suggest that the side chain of H57/H was deuterated. The joint XN refinement showed that occupancies for Dδ1 and Dε2 of H57/H were 1.0 and 0.7, respectively. However, no significant neutron scattering length density was observed around the hydroxyl oxygen Oγ of S195/H, which was close to the carboxylic carbon atom of dFPR-COOH. These observations suggest that the Oγ atom of S195/H is deprotonated and maintains its nucleophilicity in the EP complex. In addition to the active site, the hydration structures of the S1 subsite and the Exosite I, which are involved in the recognition of bivalirudin, are presented.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Taro Yamada, Kazuo Kurihara, Yuki Ohnishi, Taro Tamada, Katsuaki Tomoyori, Kenji Masumi, Ichiro Tanaka, Ryota Kuroki, Nobuo Niimura,