2001 Fiscal Year Final Research Report Summary
Structural study of [NiFe]hydrogenase
| Project/Area Number |
12680654
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
HIGUCHI Yoshiki Kyoto Univ., Graduate School of Sci., Assoc. Prof., 理学研究科, 助教授 (90183574)
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| Co-Investigator(Kenkyū-buntansha) |
HIROTA Shun Nagoya Univ. Graduate School of Sci. Assistant Prof., 大学院・理学研究科, 助手 (90283457)
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| Project Period (FY) |
2000 – 2001
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| Keywords | [Ni-Fe]hydrogenase / CO-bound hydrogenase / Hydrogen metabolism / Cryogenic diffraction study / quasi-dynamic X-ray analysis / High resolution X-ray analysis |
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| Research Abstract |
Hydrogenases catalyze the reversible oxidation of molecular hydrogen and play a key role in hydrogen metabolism in various bacteria. Hydrogenases are classified into [non-metal], [Fe], [NiFe], and [NiFeSe] hydrogenases according to the metal composition of their active sites. The [NiFe]hydrogenase from D. vulgaris Miyazaki F is composed of a heterodimer with a total molecular mass of 91 kDa. The active site of the [NiFe] hydrogenases in the oxidized form is composed of Ni and Fe atoms with four cysteinyl sulfur and four non-protein ligands (S/O, CO, CN or SO). Carbon monoxide (CO) was known as a reversible inhibitor of hydrogenases. The carbon monoxide complex of [NiFe]hydrogenase from D. v. Miyazaki has been prepared and characterized by X-ray crystallography, and absorption and Raman spectroscopy. The exogenously added CO was found to be bound to the Ni atom at the Ni-Fe active site. Distinct changes were observed in the electron density distribution of the Ni and sγ(Cys546) atoms between the CO-bound and CO-liberated structures for all the crystals tested. One of the CO-bound structures showed an additional electron density peak between the CO and Sγ(Cys546), suggesting that an intermediate of the catalytic reaction was trapped at the active site. The novel structural features found near the Ni and Sγ(Cys546) atoms suggest that these two atoms at the Ni-Fe active site play a key role during the initial process to bind H_2.
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