| Project/Area Number |
14209019
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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 |
広領域
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| Research Institution | Nagoya University |
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Principal Investigator |
WATANABE Yoshihito Graduate School of Science, Department of Chemistry, Professor, 大学院理学研究科, 教授 (10201245)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAJIMA Hiroshi Graduate School of Science, Department of Chemistry, Associate Professor, 大学院理学研究科, 助教授 (00283151)
上野 隆史 名古屋大学, 物質科学国際研究センター, 助手 (70332179)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥45,500,000 (Direct Cost: ¥35,000,000、Indirect Cost: ¥10,500,000)
Fiscal Year 2005: ¥8,190,000 (Direct Cost: ¥6,300,000、Indirect Cost: ¥1,890,000)
Fiscal Year 2004: ¥8,190,000 (Direct Cost: ¥6,300,000、Indirect Cost: ¥1,890,000)
Fiscal Year 2003: ¥8,190,000 (Direct Cost: ¥6,300,000、Indirect Cost: ¥1,890,000)
Fiscal Year 2002: ¥20,930,000 (Direct Cost: ¥16,100,000、Indirect Cost: ¥4,830,000)
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| Keywords | catalase / myoglobin / heme / high valeent / oxidation / 西洋ワサビペルオキシダーゼ / P450BSβ / 西洋わさびペルオキシダーゼ |
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| Research Abstract |
The catalase reaction has been studied in detail by using myoglobin (Mb) mutants. Compound I of Mb mutants (Mb-I), a ferryl species (Fe^<IV>=O) paired with a porphyrin radical cation, is readily prepared by the reaction with a nearly stoichiometric amount of m-chloroperbenzoic acid (mCPBA). Upon the addition of H_2O_2 to an Mb-I solution, Mb-1 is reduced back to the ferric state without forming any intermediates. This indicates that Mb-I is capable of performing two-electron oxidation of H_2O_2 (catalatic reaction). GC-MS analysis of the evolved O2 from a 50:50 mixture of H_218O_2/H_2^<16>O_2 solution containing H64D or F43H/H64L Mb showed the formation of 18O2 (m/e=36) and 16O2 (m/e = 32) but not ^<16>O^<18>O (m/e = 34). This implies that O2 is formed by two electron oxidation of H_2O_2 without breaking the O-O bond. Deuterium isotope effects on the catalatic reactions of Mb mutants and catalase suggest that the catalatic reactions of Micrococcus lysodeikticus Catalase (MLC) and F43H/H64L Mb proceed via an ionic mechanism with a small isotope effect of less than 4.0, since the distal histidine residue is located at a proper position to act as a general acid-base catalyst for the ionic reaction. In contrast, other Mb mutants such as H64X (X: A, S, and D) and L29H/H64L Mb oxidize H_2O_2 via a radical mechanism in which a hydrogen atom is abstracted by Mb-I with a large isotope effect in a range of 10 to 29, due to a lack of the general acid-base catalyst
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