1990 Fiscal Year Final Research Report Summary
Study on Regulatory Mechanisms of Anaerobically Glycolytic Enzymes of Oral Streptococci.
| Project/Area Number |
63480409
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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 |
ABBE Kazuhiko School of Dentistry, Department of Oral Biochemistry, Associate Professor., 歯学部, 助教授 (40151089)
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| Co-Investigator(Kenkyū-buntansha) |
岩見 憙道 東北大学, 歯学部, 助手 (60005030)
YAMADA Tadashi School of Dentistry, Department of Oral Biochemistry, Professor., 歯学部, 教授 (50005021)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Acid production / Streptococcus mutans / Pyruvate formate-lyase / NADPH / Streptococcous sanguis / Lactate dehydrogenase / NADH / Fructose 1, 6-bisphosphate |
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| Research Abstract |
Pyruvate formate-lyase (PFL) and lactate dehydrogenase play key roles in anaerobic sugar metabolism. PEL activity was observed among several oral bacteria including streptococi, actinomyces and lactobacilli. The active from (A-from) of PEL and the reversible inactive form (R-form) were interconvertible under anaerobic conditions. The A-form was extremely sensitive to oxygen, while the R-form was insensitive. The R-form of PEL in cell-free extract of oral streptococci was activated by an enzyme (PFL activating enzyme). The reaction required pyruvate, S-adenosyl-L-methionine, Fe^<2+>, and reducing reagent (reduced methylviologen) under anaerobic conditions. NADPH was the most effective reducing reagent in the extract of S. mutans, but less effective in S. sanguis. The NADPH dependency was unstable and lost on the purification process of the activating enzyme. However, the PFL activating enzyme regained its activity by incubating with either FAD or FMN. The PFL activating enzyme of S. Mut
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ans converted the R-form of S. Salivarius PEL into the A-form, but did not activate the S. Sanguis PEL. On thecontrary, the activating enzyme of S. Sanguis activated the S. Mutans PFL. These results suggest that the activation system of PFL was different among oral streptococci.
LDH is suspected to change in the quarternary structure by fructose 1, 6-bisphosphate (FBP) or inorganic phosphate (Pi). The enzyme was in a dimeric form without either FBP or Pi. The dimeric form of LDH was unstable. However, NADH prevented LDH from irreversible inactivation, but NADPH did not. FBP as well as Pi could convert dimer to tetramer, but Pi could not promote catalytic activitiy, i.e., Pi did not activate LDH. FBP was specific activator for LDH and Pi was potent inhibitor. Since inactivation-reactivation of LDH was observed in the permeabilized cells, the inactivation was not due to simple dilution of the enzyme. These different regulatory mechanisms of PEL and LDH were considered to control the glycolyses of oral bacteria. Less
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