1990 Fiscal Year Final Research Report Summary
Electron Carrier System and Energy Metabolism in Anaerobic Microorganisms
| Project/Area Number |
01580187
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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 |
代謝生物化学
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| Research Institution | Shizuoka University |
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Principal Investigator |
YAGI Tatsuhiko Shizuoka University, Faculty of Education, Professor, 教育学部, 教授 (00021882)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Sulfate-reducing bacterium / Electron carrier protein / High-molecular-weight cytochrome / Hemoprotein / Rubredoxin / Amino acid sequence / Anaerobic syntheses of heme / Cytochrome c-553 |
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| Research Abstract |
Effort was focused on the elucidation of the high-molecularーweight cytochrome c (hmc) among various electron carrier proteins isolated from Desulfovibrio vulgaris Miyazaki.
1. The hmc was highly purified in good yield, by eliminating the steps where the hmc was exposed to proteolytic digestion. It had been realized that the hmc was extremely susceptible to the action of proteinases present in the bacterial extract.
2. Quantitative estimation of amino acids indicated that the hmc contained 12 hemes in a single peptide of Mr : 67000.
3. The spectral properties of the hmc was similar to those of cytochrome C_3. The purity index (the alpha-peak height of the ferro-form divided by the absorbance at 280 nm) was 2.6. There was no peak at 695 nm which is a marker for the His-Met axial ligands for hemes. The reduced-minus-oxidized difference spectrum of the fully reduced hmc had a peak at 420 nm, whereas the difference spectra of partially reduced forms had double peaks at 424 and 434 nm. This indicates conformational transformation or the appearance of the high-spin form during the reduction of the hmc.
4. One of 12 hemes of hmc had a relatively positive standard redox potential, and is reduced with ascorbate. The standard redox potentials of the other hemes were estimated by redox equilibrium with FMN and calculated by means of the Nernst equation. The average E^ﾟ' value was -187 mV with an appearent n valve of 0.48 (i. e., less than unity). The redox potentials of the individual hemes were calculated from these values.
5. Partial sequences of the hmc were determined, which were homologous to those of hmc from the Hildenborough strain of D. vulgaris.
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