2005 Fiscal Year Final Research Report Summary
Structural Fluctuation and Function of Proteins Revealed by Compressibility
| Project/Area Number |
16350088
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Chemistry related to living body
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| Research Institution | HIR0SHIMA UNIVERSITY |
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Principal Investigator |
GEKKO Kunihiko Hiroshima University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (10023467)
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| Co-Investigator(Kenkyū-buntansha) |
AIDA Misako Hiroshima University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90175159)
KATAYANAGI Katsuo Hiroshima University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (20291479)
OHMAE Eiji Hiroshima University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (30284152)
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| Project Period (FY) |
2004 – 2005
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| Keywords | synchrotron / biomolecules / circular dichroism / vacuum-ultraviolet / structure analysis |
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| Research Abstract |
The vacuum-ultraviolet circular dichroism (VUVCD) spectra of various amino acids and proteins were measured using a synchrotron-radiation CD spectrophotometer at HiSOR/HSRC that is capable of measuring the CD spectra down to 140 nm in aqueous solution. L-isomers of amino acids show two successive positive peaks at around 200 and 180 nm depending on the side chain. The ab initio assignment by time-dependent density functional theory predicts that these peaks are due to n-π^* and π-π^* transitions of the carboxyl group, respectively. This analytical method was extended to assign the VUVCD spectra of other amino acids and oligopeptides. The VUVCD spectra of 31 globular proteins allowed us to estimate more accurately the content and number of α-helix and β-strand segments by extending the short-wavelength limit of the analytical program SELCON3 down to 160 nm. VUVCD spectroscopy was also applied for analysis of the structure of denatured proteins that remains not well characterized. The VUVCD spectra of metmyoglobin, staphylococcal nuclease, and thioredoxin down to 172 nm showed characteristic changes depending on the solvent conditions such as pH, temperature, and additives (to be published). Analysis using the SELCON3 program revealed quantitative differences in the secondary structures of the acid-, cold-, heat-, and guanidine-hydrochloride-denatured proteins. These results demonstrate that synchrotron-radiation VUVCD spectroscopy is a useful tool for structure analyses of biomolecules in solution based on the higher energy transitions of chromophores.
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