| Project/Area Number |
62480372
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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 School of Dentistry, Department of oral Biochemistry, Professor, 歯学部, 教授 (50005021)
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| Co-Investigator(Kenkyū-buntansha) |
ABBE Kazuhiko School of Dentistry, Department of oral Biochemistry, Associate Professor, 歯学部, 助教授 (40151089)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥3,600,000 (Direct Cost: ¥3,600,000)
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| Keywords | Dental caries / Mutans streptococci / Dental plaque / Acid production / Anaerobic sugar metabolism / Lactate dehydrogenase / Oral microorganism / Pyruvate formate-lyase / 歯垢微生物 / ピルビン酸ギ酸リア-ゼ / NADPH / ピルビン酸ギ酸リアーゼ / 歯垢微生物の糖代謝 / Streptococcus mutans / Sterptococcus sanguis / 再活性化酵素 / ウ蝕 / 高度嫌気条件 / Streptococcus sanguis / 糖代謝 / 酵素の型変換 |
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| Research Abstract |
The environment of oral cavity changes greatly from time to time. Thus acid production In dental plaque, an inevitable event for the initiation and progression of dental caries, is affected by this change of environment. We studied the effect of possible change of oral environment on the acid production of oral microorganisms, such as streptococcal, actinomyces and lactobacilli.
The pH in dental plaque drops during meals due to the uptake of sugars. At neural pH streptococci have been known to produce formic andacetic acids in addition to ethanol when supply of sugar is limited. But at pH 5.5 streptococci produced mainly lactate even if supply on sugar is limited and even under strictly anaerobic conditions. The lactate dehydrogenase (LDH), a key enzyme of lactate production , of streptococci was found to be induced at low pH, while pyruvate formate-lyase (PFL), a key enzyme of formic and acetic acids production under strictly anaerobic conditions, was not induced. The optimum PB of the LDH was lower than that of PFL. Thus the low pH in the cells of streptococci was also considered responsible for this change into lactate fermentation at low pH. PFL is activated under anaerobic conditions in the presence of fermentable sugar. For this activation NADPH was found to be an essential factor. This means that the activation PFL, an important enzyme of anaerobic sugar metabolism, is finely regulated during sugar metabolism of streptococci. A presence and a similar regulation of PFL were also found in Actinomyces naeslundii, Actinomyces viscosus. Lactobacillus cases and Streptococcus lactis.
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