| Project/Area Number |
05454496
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
YAMADA Tadashi Tohoku University School of Dentistry, Professor, 歯学部, 教授 (50005021)
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| Co-Investigator(Kenkyū-buntansha) |
ABBE Kazuhiko Tohoku University School of Dentistry, Associate Prof., 歯学部, 助教授 (40151089)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1993: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Keywords | Dental-caries / Anaerobic-conditions / Mutans-streptococci / Anaerobes / Oral-microorganism / Oxygen-sensitive-enzyme / Periodontal-disease / Ribonucleoside-triphosphate-reductase / リボヌクレオシドミリン酸還元酵素 / ピルビン酸ギ酸リアーゼ / 歯垢 / 酸産生 / 酵素の活性調節 / 嫌気グローブボックス |
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| Research Abstract |
Ribonucleoside triphosphate reductase is an only one enzyme that catalyzes the reaction to synthesize deoxyribonucleotides in anaerobic microorganisms. This enzyme is an essential enzyme for growth and survival of these microorganisms, because deoxyribonucleotides are material for DNA synthesis. The activity of this enzyme has been measured with radio isotopes. However, the accurate measurement of the activity was diffcult, because this enzyme is extremely oxygen-sensitive and usage of radioisotopes in an anaerobic glove box is legally difficult especially in Japan. We could first develop a method to estimate the activity of this enzyme by photometric method with diphenylamine as a color producing reagent in the cell-free extracts of Escherichia coli. With this method we then find the activity of this enzyme in an oral microorganism, Streptococcus mutans, a strong cariogenic bacterium. To estimate the activity more accurately, we uesd high performance liquid chromatography. Then, we found that the enzyme in S.mutans is also highly oxygen-sensitive and that this enzyme has a reversible inactive form. The inactive form of this enzyme was activated by a similar way as found in another highly oxygen-sensitive enzyme, pyruvate formate-lyase. It is possible that the same activating enzyme activates these two oxygen-sensitive enzymes. These findings sugggest that the variable oxygen concentration in dental plaque affects strongly the activities of these enzymes and then the microorganisms involved in the initiation and development of dental caries as well as periodontal diseases.
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