Dissociation constants of lipid ionizable groups II. Changes in surface pK at low ionic strengths Export

@article{citeulike:2298220, abstract = {Surface dissociation constants (pKs) for the PO4- group in dioleoylphosphatidylglycerol (DOPG) and the COO- group in phosphatidylserine (PS) bilayer membranes were found by fitting theoretical curves to the experimental dependences of electrophoretic mobilities (EPMs) on ionic strength (C) and pH in solutions of monovalent salts. The measured EPMs were expressed in potential units through the Smoluchowsky equation; the corresponding [xi]sm values were used as experimental points. The [xi]sm vs. log C curves were obtained for DOPG in KCl and for PS in NaCl solutions at pH 7 in the range 10-3-1 M; the [xi]sm vs. pH curve was measured for PS in 2 x 10-2 M NaCl in the pH range 2-7. Theoretical analogues of [xi]sm were calculated from the Dukhin-Deryaguin equation, which takes into account the mobility decrease due to the relaxation effect. For both lipids, fitting to the [xi]sm vs. log C curves, with due regard for cation adsorption, allowed us to find changes in th pKs values at low ionic strengths (below 10-1 M). For DOPG, changes in pKs were verified by comparison of the related surface potential ([psi]s) vs. log C curve with [Delta][psi]s vs. log C curves measured on DOPG planar lipid membranes. Analysis of the [xi]sm vs. pH curve for PS showed that a single pKs value cannot be obtained from the fitting procedure; this is interpreted as an indication of a change in pKs with pH, in agreement with predictions made in Part I of this paper.}, author = {Egorova, E. M.}, citeulike-article-id = {2298220}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/S0927-7757(96)03959-3}, citeulike-linkout-1 = {http://www.sciencedirect.com/science/article/B6TFR-3SR4KGR-F/2/30e4bbb9f0972d809da4b47a1cdd4052}, day = {1}, doi = {10.1016/S0927-7757(96)03959-3}, journal = {Colloids and Surfaces A: Physicochemical and Engineering Aspects}, keywords = {anionic, cardiolipin, cationic}, month = {January}, number = {1-3}, pages = {19--31}, posted-at = {2008-01-28 16:06:28}, priority = {2}, title = {Dissociation constants of lipid ionizable groups II. Changes in surface pK at low ionic strengths}, url = {http://dx.doi.org/10.1016/S0927-7757(96)03959-3}, volume = {131}, year = {1998} }

TY - JOUR ID - citeulike:2298220 L3 - citeulike-article-id:2298220 N2 - Surface dissociation constants (pKs) for the PO4- group in dioleoylphosphatidylglycerol (DOPG) and the COO- group in phosphatidylserine (PS) bilayer membranes were found by fitting theoretical curves to the experimental dependences of electrophoretic mobilities (EPMs) on ionic strength (C) and pH in solutions of monovalent salts. The measured EPMs were expressed in potential units through the Smoluchowsky equation; the corresponding [xi]sm values were used as experimental points. The [xi]sm vs. log C curves were obtained for DOPG in KCl and for PS in NaCl solutions at pH 7 in the range 10-3-1 M; the [xi]sm vs. pH curve was measured for PS in 2 x 10-2 M NaCl in the pH range 2-7. Theoretical analogues of [xi]sm were calculated from the Dukhin-Deryaguin equation, which takes into account the mobility decrease due to the relaxation effect. For both lipids, fitting to the [xi]sm vs. log C curves, with due regard for cation adsorption, allowed us to find changes in th pKs values at low ionic strengths (below 10-1 M). For DOPG, changes in pKs were verified by comparison of the related surface potential ([psi]s) vs. log C curve with [Delta][psi]s vs. log C curves measured on DOPG planar lipid membranes. Analysis of the [xi]sm vs. pH curve for PS showed that a single pKs value cannot be obtained from the fitting procedure; this is interpreted as an indication of a change in pKs with pH, in agreement with predictions made in Part I of this paper. IS - 1-3 JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects EP - 31 TI - Dissociation constants of lipid ionizable groups II. Changes in surface pK at low ionic strengths VL - 131 SP - 19 KW - anionic KW - cardiolipin KW - cationic AU - Egorova, EM PY - 1998/01/01/ UR - http://dx.doi.org/10.1016/S0927-7757(96)03959-3 ER -