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

Nakamura, Akihiko  ,  Ishida, Takuya  ,  Kusaka, Katsuhiro  ,  Yamada, Taro  ,  Fushinobu, Shinya  ,  Tanaka, Ichiro  ,  Kaneko, Satoshi  ,  Ohta, Kazunori  ,  Tanaka, Hiroaki  ,  Inaka, Koji  ,  Higuchi, Yoshiki  ,  Niimura, Nobuo  ,  Samejima, Masahiro  ,  Igarashi, Kiyohiko  ,  中村, 彰彦  ,  石田, 卓也  ,  日下, 勝弘  ,  山田, 太郎  ,  伏信, 進矢  ,  田中, 一郎  ,  金子, 哲  ,  太田, 和敬  ,  田仲, 広明  ,  伊中, 浩治  ,  樋口, 芳樹  ,  新村, 信雄  ,  鮫島, 正弘  ,  五十嵐, 圭日子

1 ( 7 ) 2015-08-21 , American Association for the Advancement of Science , 米国科学振興協会(AAAS)
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.
Physical characteristics: Original contains color illustrations
形態: カラー図版あり

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