1999 Fiscal Year Final Research Report Summary
Investigation of homochiral origin on the basis of comparison between enzymatic activity and active site for both enantiomers
Project/Area Number |
10680560
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
Bioorganic chemistry
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Research Institution | University of Tsukuba |
Principal Investigator |
SHIMADA Akihiko University of Tsukuba, Institute of Applied Biochemistry, assistance professor, 応用生物化学系, 講師 (90235614)
|
Project Period (FY) |
1998 – 1999
|
Keywords | tryptophanase / chiral homogeneity / D-tryptophan / diammoniumhydrogen phosphate |
Research Abstract |
Experiments were performed to identify the relative position of an active site for D-tryptophan with that for L-tryptophan, and the following results were obtained. 1. D-tryptophan was not racemized at all in highly concentrated diammoniumhydrogen phosphate solution. 2. The inhibition types of potassium pyruvate and indolepyruvate were analyzed for L-tryptohan degradation reaction. The former was competitive, but the latter switched from competitive to noncompetitive type with increasing diammoniumhydrogen phosphate concentrations. 3. γ-tryptophanase, which was inactivated to D-tryptophan due to γ-ray irradiation, inhibited competitively even in the presence of diammoniumhydrogen phosphate. 4. On the basis of the above results, positional relationship between an active site for D-tryptophan and one for L-tryptophan could be illustrated as follows. That is, heterocyclic moiety of D-tryptophan binds with another binding site remote from a binding site for L-tryptophan. The location of D-tryptophan has an appropriate angle to react with tryptophanase. Thus, D-tryptophan can become to tryptophanase. 5. Although the stereoselectivity of enzyme has been ever considered to be permanently strict, it was shown by this study that environmental change around the enzyme made it ambiguous. 6. We will investigate how a structural change effective to chirally stereoselective change is.
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Research Products
(12 results)