1998 Fiscal Year Final Research Report Summary
The Mechanism of the Highly Cooperative Intramolecular Transition for Aspartates by Using Homo-oligopeptides
| Project/Area Number |
09650990
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
高分子構造・物性(含繊維)
|
|---|
| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
|---|
Principal Investigator |
FURUYA Hidemine Tokyo Institute of Technology, Department of Polymer Chemistry, Associate Professor, 工学部, 助教授 (90251652)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | Aspartate / Oligopeptide / Helix-helix Transition / Highly Cooperative Intramolecular Transition / Conformation / NMR measurement |
|---|
| Research Abstract |
Poly(beta-phenethyl L-aspartate)(PPLA) can be either in the right- or left-handed arrangement depending on the solvent or temperature. In our previous study, PPLA was found to transform from the right- handed to the left-handed alpha-helix in tetrachioroethane (TCE) with an increase in temperature. The transition takes place in the dilute isotropic solution as well as in the anisotropic liquid-crystalline state around 80。C.In the presence of a denaturant acid, PPLA also exhibits a transformation to the left- handed form by lowering temperature. The primary cause responsible for a highly cooperative helix-helix transition was found to reside in a small free-energy difference in the conformational states of the side chain. In this work, the mechanism of the highly cooperative helix sense reversal has been investigated by using homo-oligopeptide model compounds. The chain length dependence for oligopeptides bounded to polyethyleneglycol was studied by CD and NMR measurements. The short chain oligomers form beta-sheet structure. The oligomers containing more than 18 residues prefer to be alpha-helix. The place of the chain where the helix transition begins to occur was studied by introducing of blockpolymers. Blockpolymers consist of poly(gamma-benzyl L-glutamate) which never exhibit the helix sense inversion. From the results, the helix-helix transition was found to take place from the terminal of the aspartate chain.
|
