2004 Fiscal Year Final Research Report Summary
Contribution of D-Aspartic Acit to formation of indigestible aggregate of protein
| Project/Area Number |
15580107
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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 |
Food science
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| Research Institution | Kyoto University |
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Principal Investigator |
MATSUMURA Yasuki Kyoto University, Graduate School of Agriculture, Professor, 農学研究科, 教授 (50181756)
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| Project Period (FY) |
2003 – 2004
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| Keywords | D-aspartic acid / indigestible aggregate / conformational change / β-sheet structure / human tau protein / amyloid fibril / spray drying / dissociation of protein aggregate |
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| Research Abstract |
Recently, indigestible aggregate of protein is found to be closely relating to the "folding disease" such as prion, Alzheimer disease, but the mechanism of protein aggregation remains unclear. Transformation from L-aspartic acid(L-Asp) to D-aspartic acid(D-Asp) is suggested to be one reason for such aggregate formation. In this study, the following experiments are carried out in order to understand the effects of the transformation to D-Asp on the conformation of model peptides or proteins, and the following aggregation of peptides or proteins.
Several kinds of peptides with amino acid residues varying from 10 to 30 were synthesized. We compared the conformation of peptides including only L-amino acids and the cohort peptides in which L-Asp was displaced by D-Asp using CD and FT-IR spectroscopy. The formation of amyloid fibril was also probed by the binding of fluorescent dye. For most of peptides, the substitution to D-Asp enhanced the formation of inter-molecular β-sheet. Human tau protein was found to form the amyloid fibril by the substitution to D-Asp, suggesting that D-Asp is closely related to the formation of indigestible aggregates of proteins.
In this study, we also investigated the occurrence of D-Asp in the protein aggregate in food proteins by several food processing conditions, and the way to dissociate such aggregates to monomeric forms. We found that the heating above glass transition temperature is effective to cause the refolding the secondary structure from inter-molecular β-sheet to α-helix structure, thereby dissociating the aggregates induced by spray-drying.
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