» Articles » PMID: 41238

Hydrophilic Region of Lecithin Membranes Studied by Bromothymol Blue and Effects of an Inhalation Anesthetic, Enflurane

Overview
Specialty Science
Date 1979 Oct 1
PMID 41238
Citations 1
Authors
Affiliations
Soon will be listed here.
Abstract

A pH-indicator dye, bromothymol blue, was used to probe the hydrophilic surface of dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine bilayer vesicles. The apparent pK of the surface-adsorbed dye was larger than the bulk pK value. The contribution of the choline positive charge on the dissociation constant of the dye adsorbed on the vesicle surface was estimated by screening the charge interaction with 2 M KCl. The effective surface potentials interacting with the dye were thus estimated to be 33.2, 45.6, and 46.8 mV, respectively, for the dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine vesicles. From the differences between the obtained effective potentials and the calculated surface potentials of the charge-determining plane of the choline head, the distances between the prototropic part of the dye and the choline charge-determining plane were estimated to be 10.5, 8.0, and 7.8 A, respectively. These values were obtained at 25 degrees C; the dimyristoylphosphatidylcholine membrane was in the liquid-crystalline phase and the other two were in the solid gel phase. Addition of an inhalation anesthetic, enflurane, decreased the distance in the dimyristoylphosphatidylcholine vesicles and increased the distance in the dipalmitoyl- and distearoylphosphatidylcholine vesicles. The increase of precessional motion of choline head by the inhalation anesthetic is apparently responsible for the changes.

Citing Articles

Reaction kinetics in living systems.

EYRING H, Ma S, Ueda I Proc Natl Acad Sci U S A. 1981; 78(9):5549-53.

PMID: 6946491 PMC: 348783. DOI: 10.1073/pnas.78.9.5549.

References
1.
Yeagle P, Hutton W, Huang C, Martin R . Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study. Proc Natl Acad Sci U S A. 1975; 72(9):3477-81. PMC: 433017. DOI: 10.1073/pnas.72.9.3477. View

2.
Shieh D, Ueda I, Lin H, EYRING H . Nuclear magnetic resonance studies of the interaction of general anesthetics with 1,2-dihexadecyl-sn-glycero-3-phosphorylcholine bilayer. Proc Natl Acad Sci U S A. 1976; 73(11):3999-4002. PMC: 431300. DOI: 10.1073/pnas.73.11.3999. View

3.
Gupa S, Govil G . Molecular orbital studies on the conformation of phospholipids. II. Preferred conformations of hydrocarbon chains and molecular organization in biomembranes. J Theor Biol. 1975; 51(1):13-34. DOI: 10.1016/0022-5193(75)90136-8. View

4.
Gally H, NIEDERBERGER W, Seelig J . Conformation and motion of the choline head group in bilayers of dipalmitoyl-3-sn-phosphatidylcholine. Biochemistry. 1975; 14(16):3647-52. DOI: 10.1021/bi00687a021. View

5.
Jendrasiak G, Mendible J . The phospholipid head-group orientation: effect on hydration and electrical conductivity. Biochim Biophys Acta. 1976; 424(2):149-58. DOI: 10.1016/0005-2760(76)90184-3. View