1989 Fiscal Year Final Research Report Summary
Neutron Diffraction Studies on Penetration of Water into Phospholipid Bilayers
| Project/Area Number |
63580210
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | GUNMA UNIVERSITY |
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Principal Investigator |
YABUKI Sadato GUNMA UNIVERSITY, FACULTY OF GENERAL STUDIES PROFESSOR, 教養部, 教授 (50011581)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Kohei IBARAKI UNIVERSITY, FACULTY OF EDUCATION PROFESSOR, 教育学部, 教授 (80008226)
TAKIZAWA Toshiharu GUNMA UNIVERSITY, FACULTY OF GENERAL STUDIES PROFESSOR, 教養部, 教授 (50008158)
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| Project Period (FY) |
1988 – 1989
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| Keywords | neutron diffraction / small angle neutron scattering / hydrophilic phospholipid / triphosphoinositide / phosphatidylinositoldiphosphate / phospholipid bilayer / water |
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| Research Abstract |
Experimental (1) Highly purified ammonium salts of very hydrophilic phospholipid, triphosphoinositide (TPI), were prepared from bovine brain. (2) Newly designed cells were used for measurements by the small angle neutron scattering spectrophotometer SAN at Booster station of the National Laboratory for High Energy Physics in Tsukuba. (3) Small angle neutron scattering measurements were made for TPI multibilayers with different water content (0-100 wt% ; 100% D_2O or 50% D_2O) at different temperatures (10ﾟC and 40ﾟC) and with or without Ca ions.
Results and Analysis Scattering profiles with two or three reflection peaks were obtained for all cases. Model fitting was made to reproduce the observed reflections by taking into account the water content dependence of lamellar spacing-revealed by X-ray scattering : existence of various numbers of water molecules was assumed in each of three regions of TPI multibilayers, i.e., in head group layers and tail group layers, and between bilayers.
Conclusion Direct structural evidences to show the water penetration into the hydrophobic interiors of TPI bilayers (the object of this project) were successfully obtained (1) The best fit between the calculated and observed reflections was obtained for a strip model which allows water to penetrate into hydrophobic interior region of each TPI bilayer. (2) Water molecules appear unable to stay in the hydrophobic interior at temperatures above 40ﾟC. (3) Water molecules seem to be kept out from the interior in the presence of Ca ions.
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