2001 Fiscal Year Final Research Report Summary
Characterization of denitrifying enzymes in photosynthetic bacterium
| Project/Area Number |
11460036
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | The University of Tokyo |
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Principal Investigator |
OKUBO Akira Graduate School of Agriculture Life Sciences, The University of Tokyo, Professor, 大学院・農学生命科学研究科, 教授 (20111479)
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| Co-Investigator(Kenkyū-buntansha) |
ABO Mitsuru Graduate School of Agriculture Life Sciences, The University of Tokyo, Lecturer, 大学院・農学生命科学研究科, 講師 (00272443)
YAMAZAKI Sunao Nagasaki University, Faculty of Environmental Studies, Professor, 環境科学部, 教授 (00011982)
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| Project Period (FY) |
1999 – 2001
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| Keywords | denitrification / multi-cupper enzyme / Rhodobacter sphaeroides f.sp. denitrificans / nitrous oxide |
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| Research Abstract |
Rhodobacter sphaeroides f. sp. denitrificans IL 106 is the first isolated strain as a photosynthetic denitrifying bacteria, which can grow depending on a variety of energy-generating systems, i.e., not only denitrification, but also O_2 respirarion, dimethyl sulfoxide respiration and photosynthesis.
Denitrifying enzymes in this photosynthetic bacterium,were studied. Nitrous oxide reductase (N_2OR), nitrite reductase (NIR) and nitric oxide reductase (NOR) were examined. Especially, N_2OR was intensively studied and characterized.
The N_2OR from this strain was purified by ammonium sulfate fractionation, gel filtration chromatography and anion exchange chromatography. This purified enzyme is composed of two identical subunits and contains four copper atoms per subunit. The subunit molecular mass was 66 kDa determined by MALDI-TOF-MS. By means of ESR measurement, this enzyme contains at least three types of copper centers, namely, CU_A, Cuz_1 and Cuz_3. The CU_A center, which is different from Cu(type 1) or Cu(type 2) and found only in N_2OR and cytochrome oxidase, was found in this enzyme and supposed to play a role in electron transfer.
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