| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Research Abstract |
Using synthetic amphiphiles and synthetic polypeptide, artificial simulation of structure and function of biological membrane was studied. As the components of bilayer membrane, distearyl dimethyl ammonium chloride (DSPNa) having the positive head group, and sodium distearyl dime- thyl phosphate (DSPNa) and oleylamine both of which had the negative head groups are selected. As the model proteins, poly(L-glutamic acid) (PLGA) having negatively charged side chains, rel-atively nonpolar poly( <gamma> -methyl L-glutamate) (PMLG), copoly(methyl glutamate-glutamic acid) (CopolyMG-GA), copoly( <gamma> -stearyl L-glutamate) (CopolySG-GA) having long nonpolar side chains, and azo-modified Copoly(azo-MG-GA) which respondeds to irradiation of ultraviolet rays. Though DSACl forms stable vesicle type bilayer membranes in water, DSPNa needs choresterol, and oleylamine needs n-decan, as the auxiliary substances for bilayer formation. Clear gel - liquid cryatal transitions and the existence of bound w
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ater to the head groups of all these amphiphiles were explored. PMLG molecules penetrate the bilayer membranes of all the examined amphiphiles at a right angle to membrane surface. PLGA molecules in DSACl system exist on the membrane surface with the ionic interactions between their side chaines and head groups of amphiphiles. PLGA in DSPNa system exists more apart from the membrane surface. CopolyMG-GA molecules ditribute both in the membrane and on the membrane surface, and an analysis of temperature dependency of the distribution coefficients for Copoly(MG-GA)'s with various GA contents shows that the interactions between GA parts of the copolymer and head groups of amphiphiles have the principal contribution for the ditribution of the copolymer. It is clarified with the study of fluorescence spectroscopy that PMLG and CopolyMG-GA molecules associate in bilayer membranes, and the association of the copolymer molecules is excellent for ion transport through bilayer membrane compared with the case of single molecule. Azo-groups in Copoly azo-MG-GA included in DSACl bilayer membrane takes cis-form, which is more polar than its trans-form, with irradiation of ultraviolet rays. As a consequence, the exclusion of the cololymer molecules from the inside of bilayer to the membrane surface occurs, which causes the decrease of ion permeability through bilayer membranes. Furthermore, an aggregation of vesicles occurs with the interaction between GA groups of the copolymer and the head groups of bilayer molecules. Less
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