| Project/Area Number |
06680551
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bioorganic chemistry
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SHIMADA Akihiko Univeristy of Tsukuba, Institution of Applied Biochemistry, assistant Professor, 応用生物化学系, 講師 (90235614)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | origin of optical activity / selection mechanism for optical isomers on enzyme / D-tryptophan / tryptophanase / diammoniumhydrogen phosphate / 光学活性の起源 / リン酸水素2アンモニウム / 生命の起原 / アミノ酸光学異性体の選択 |
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| Research Abstract |
We had elucidated the reaction pathway of tryptophanase-catalysed degradation of D-tryptophan in the presence of diammoniumhydrogen phosphate and had studied selection mechanism of D-amino acids on enzyme for the term of this project. Information newly obtained from this research is described below.
1.Diammoniumhydrogen phosphate ((NH_4) _2HPO_4) acted on tryptophanase as an activator below 50% saturation, but as a noncompetitive inhibitor above 50% saturation.
2.Reaction pathway was satisfactorily clarified on the basis of kinetic analysis. Tryptophanase bound at random with D-tryptophan and (NH_4) _2HPO_4 in rapid equilibrium. D-tryptophan was degraded through tryptophnase・D-tryptophan・ (NH_4) _2HPO_4 complex.
3.D-tryptophan bound with tryptophanase in the absence of (NH_4) _2HPO_4. Increasing concentration of (NH_4) _2HPO_4 changed inhibition type from competitive type through mixed type to uncompetitive type.
4.The above result indicated that binding site and catalytic site within active site of tryptophanase was independent. In addition, it was suggested that the binding site of D-tryptophan independently behaved for that of L-tryptophan.
5.Results so far obtained have been reported in papers.
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