ACTIVATION MECHANISM OF SOLUBLE GUANILATE CYCLASE FROM BOVINE LUNG
| Project/Area Number |
06680658
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biophysics
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
MAKINO Ryu Himeji Institute of Technology, Department of Life Science, Associate Professor, 理学部, 助教授 (40101026)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | GUANYLATE CYCLASE / NITRIC OXIDE / FERROUS NO COMPLEX / EPR SPECTRUM HEME PROTEIN / 電子常磁性共鳴 / 一酸化炭素 / 酵素の活性調節 |
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| Research Abstract |
Soluble guanylate cyclase has been purified to apparent homogeneity from bovine lung. The purified enzyme was a heterodimer and contained 1 protoheme IX/heterodimer. Optical spectral analyzes of the enzyme heme suggested that the ferric, ferrous and ferrous NO forms were 5-coordinate, while ferrous CO and cyanide forms were in a 6-coordinate state. EPR studies confirmed that the ferric enzyme was in a pure 5-coordinate high spin state, which converted to a 6-coordinate low spin state upon binding of cyanide. The NO complex exhibited the 3-line EPR signal typical of a 5-coordinate state. Among these species examined, the ferrous NO complex only exhibited a marked activity, while other species were practically inactive except for the CO complex being 5 times more active than the basal state.
When the binding of NO to the ferrous enzyme was examined by a stopped flow method, a 6-coordinate NO complex with 419 nm Soret peak was found to be transiently formed and then converted to the 5-coordinate NO complex with a half life of about 25 msec. The binding rate constant of NO to the ferrous enzyme was estimated over 10^7 M^<-1> sec^<-1>, which was about 1000 times greater than that for the CO binding. These results indicate that the heme bound NO triggers the weakening or breaking of the iron-proximal ligand bond, resulting in the formation of the 5-coordinate NO complex. Thus, the modulation of the iron-proximal ligand bond by the NO binding was essential for the activation, but the binding of other ligands including CO did not cause appreciable changes in the iron-proximal bond.
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Report
(3 results)
Research Products
(14 results)
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[Publications] Shimada, H., Makino, R., Unno, M., Horiuchi, T., and Ishimura, Y: "Proton and Electron Transfer Mechanisms in Dioxygen Activation by Cytochrome P450cam" in Cytochrome P450 (Lechner, M.C., ed.) John Libby Eurotext, Paris. 299-306
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「研究成果報告書概要(欧文)」より
Related Report
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[Publications] Shiro, M., Fujii, M., Isogai, Y., Adachi, S., Iizuka, T., Makino, R., Obayashi, E., Nakahara, K., and Shoun, H.: "Iron-ligand Structures and Redox Properties of Nitric Oxide Reductase Cytochrome P450nor from Fusarium oxysporum : Relevance to Its NO Reduction Activity" Biochemistry. 34. 9052-9058 (1995)
Description
「研究成果報告書概要(欧文)」より
Related Report
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