| Project/Area Number |
04671120
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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 |
Functional basic dentistry
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
ABE Kazuhiko Tohoku Univ, School of Dentistry, Associate Professor., 歯学部, 助教授 (40151089)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Pyruvate formate-lyase / Streptococcus mutans / Streptococcus sanguis / Acid production / Sorbitol / PFL activating enzyme / Selenium / PFL inactivating enzyme / ピルビン酸ギ酸リアーゼ / Streptococcus mutanら / 糖代謝 / スクロース / NADH / 歯垢 / ピルビン酸ギ酸リアーゼ活性化酵素 / ピルビン酸ギ酸リアーゼ不活性化酵素 / 嫌気糖代謝 / 酸素感受性酵素 / NADPH / 口腔レンサ球菌 / 高度嫌気条件 |
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| Research Abstract |
Pyruvate formate-lyase (PFL) is a key enzyme of production of formic and acetic acid and ethanol by streptococci under anaerobic conditions. PFL was converted between oxygen-sensitive, active and oxygen tolerant, inactive forms in the cells of Streptococcus sanguis but not in the cells of Streptococcus mutans. All PFL was kept active in S.mutans cells. The biochmical mechanism of this difference in the interconversion was investigated. NADPH was the most efficient reducing agent for the activation of the inactive PFL of S.mutans. On the contrary, NADPH was not so efficient in S.sanguis. Fe^<2+> and selenium were required for PFL activating enzyme, and protein radial was involved in the active center of PFL.PFL inactivating enzyme, which converted active form to oxygen-tolerant inactive form, was found in streptococci. S.sanguis had higher activity of PFL inactivating enzyme than S.mutans.
Intracellular conversion of PFL could be explained by these findings. Minute levels of pyruvate and inorganic phosphate inhibited the activity of PFL inactivating enzyme and kept active form of PFL.However, CoA enhanced PFL inactivation. These regulatory mechanism could be important teleologically. Glucose or sucrose metabolism was inhibited by sorbitol in S.mutans under certain conditions. The incorporation of sorbitol resulted in high NADH/NAD ratio and inhibited streptococcal sugar metabolism, since PFL activity was not enough to keep the oxidation/reduction balance. Sorbitol also inhibited sugar metabolism of microorganisms in dental plaque in situ.
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