1998 Fiscal Year Final Research Report Summary
Structural Biology of multi-heme protein from ammonia oxidizing bacterium
| Project/Area Number |
09660076
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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 |
応用微生物学・応用生物化学
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| Research Institution | Kanazawa University |
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Principal Investigator |
FUKUMORI Yoshihiro Kanazawa University, Faculty of Science, Professor, 理学部, 教授 (60135655)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Nobuo Tokyo Institue of Technology, Faculty of Bioscience and Biontechnology Professor, 生命理工学部, 教授 (50032024)
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| Project Period (FY) |
1997 – 1998
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| Keywords | respiratory proteins / cytochrome / heme / ammonia / hydroxylamine / Nitrosomonas / nitrification / respiratory chain |
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| Research Abstract |
(1)Crystalographic studies on cytochrome c-554 and cytochrome c-552.
We investigated the conditions for cyrstallization of cytochrome c-554 and c-552. Although the amorphous precipitates were obtained from cytochrome c-552 preparation, no crystals could not be prepared from cytochrome c-554.
(2)Mechanism of intra- and inter-electron transfers in the multi-heme protein.
It is generally accepted that the "NOH" is produced as an intermediate in the oxidation of hydroxylamine to nitrite by the hydroxylamine oxidoreductase. This strongly suggest that the two steps of two-electron transfer in the molecule is precisely occurred. However, the hydroxylamine oxidoreductase has only hemes c as prosthetic groups in the molecule which is one electron transfer component. In 1998, we tried to elucidate the molecular mechanism of electron transfer in the hydroxylamine oxidoreductase on the basis of the crystal structure. We found that the enzyme is a trimer and each monomer has 8 hemes c in the molecule, indicating that the enzyme has totally 24 hemes c in the molecule. The hemes are aligned to form a ring as heme-cluster in the molecule. One is triple heme-cluster which is composed to be a substrate-binding heme c, P460, and two hemes c. Another is double heme-cluster. The monomer has one triple-heme cluster, two double heme-clusters and one heme c in the molecule, suggesting that the electron transfer is triple-heme cluster * double heme-cluster * double heme-cluster. The characteristic heme arrangement has been elucidated in the present study.
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