1997 Fiscal Year Final Research Report Summary
X-ray crystallographic studies on molecular mechanism of Oxygen respriration
| Project/Area Number |
08408026
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | Osaka University |
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Principal Investigator |
TSUKIHARA Tomitake Institute for Protein Research, Osaka University, Professor, たんぱく質研究所, 教授 (00032277)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAI Hiroaki Institute for Protein Research, Osaka University, Assistant, たんぱく質研究所, 助手 (00272162)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Crystal structure / Cytochrome c oxidase / oxidized cytochrome c oxidase / reduced cytochromec oxidase / Membrane protein / アジド結合型チクトロムC酸化酵素 / 膜蛋白質 |
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| Research Abstract |
Crystal structures of cytochome c oxidase from bovine heart at various states are determined. Fully oxidized state was at 2.3*resolution ; fully reduced state, 2.35* ; CO bound fully reduced state, 2.8* ; azide bound fully oxidized state, 2.9*.
Crystal structure analysis of the fully oxidized enzyme at 2.3* resolution revealed that (1) a peroxide group bridges Fea3 and CuB dinuclear center which is an oxygen reduction site, (2) His240, one of the ligands of CuB,and Tyr244 are linked by a covalent bond, (3) there exist water molecules contributing electron and proton transfer, (4) Na or Ca ions are located within the enzyme melecule, (5) the enzyme forms dimeric structure stabilized by cardiolipin molecules, (6) trans-membrane a-helices are abundant in glycine residues at 7%, which do not break a-helices.
Crystal structure analysis of fully reduced enzyme at 2.35* resolution elucidated that (1) the oxygen reduction site has no ligand, (2) the residues fro Gly49 to Asn55 of subunit I in reduced state are different from those in oxidized state in their conformation.
Crystal structure analysis of the CO bound fully reduced enzyme at 2.8* resolution revealed that (1) CO group ligates Fea3, and (2) the residues Gly49 to Asn55 of subunit I are similar to those of the reduced state in their conformation.
Crystal structure analysis of the azide bound oxidized form at 2.9* resolution revealed that (1) azide groups bound at the oxygen reduction site and a molecular surface of the enzyme, and (2) all the histidine residues which ligate to the CuB do not have multiple conformational states in contrast to those of the bacterial enzyme.
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