| Project/Area Number |
04404095
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
生物物性学
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| Research Institution | Osaka University |
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Principal Investigator |
YUTNAI Katsuhide Insitute for Protein Research, Osaka University, Associate Professor, 蛋白質研究所, 助教授 (90089889)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥24,000,000 (Direct Cost: ¥24,000,000)
Fiscal Year 1993: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1992: ¥20,000,000 (Direct Cost: ¥20,000,000)
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| Keywords | Tryptophan Synthase / Protein Protein Interaction / Protein Complex / Titration Calorimetry / Ligand Binding / Molecular Recognition / 等温滴定型カロリメータ / プロリン |
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| Research Abstract |
Tryptophan synthase aipha/beta subunit complex has been used as a model system for exploring molecular recognition in protein-protein interaction. Each of the alpha and beta_2 subunits has an inherent catalytic function. When the alpha and beta_2 subunits combine to form the alpha_2beta_2 complex, alpha and beta enzymatic reactions for each subunit are stimulated by one to two orders of magnitude. The mutual activation machanism of the complex has been studies by titration calorimetry. Research results are followings. 1) The binding constant of aipha subunit to the first site of beta_2 subunits was remarkably different from that of the second site. The analysis for DELTACp predicts folding(from denatured state in the local region) of about 120 residues on the association of alpha subunit with beta_2 subunits. These results suggest that the formation of alpha/beta subunit complex can be described by an "induced-fit" model. 2) The alpha subunits that have an amino acid substitution at a residue in the interface between the alpha and beta_2 subunit exhibit greatly reduced affinities for the beta_2 subunit. Calorimetric analysis indicates that the decrease in the binding constant is caused by enthalpic effects. 3) The mutant alpha subunit at a residue far from the interface affected both binding constant and binding enthalpy, suggesting that long rang effect is also important on the association.
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