Micelle Formation by Lecithin in Some Aliphatic Alcohols

Abstract

Lecithin has been studied in methanol, ethanol, butanol, and hexanol using light scattering and viscosity techniques. A new type of light scattering cell was employed. Micelles were present in all solvents, the micellar weights being 2,300; 7,100; 18,000, and 22,000 in the four alcohols respectively. It appeared that as the polarity of the solvent decreased, the micellar size increased. Dissymmetry measurements showed that no dimension of the micelles exceeded 270A (A/20), but high observed depolarisations showed that the particles were anisotropic. Viscosity measurements also gave an idea of the shape of the micelles, giving intercepts of plots of specific viscosity/solute volume fraction against solute volume fraction of 4.29, 4.26, 4-26, and 3.56 for the four alcohols respectively. Using the dimensions of the lecithin molecule, and the number of monomers present in the micelle, calculations of the theoretical viscosity intercept have been made for each solvent, and compared with values obtained experimentally.MICELLE formation by lecithin in benzene has been studied (Elworthy, 1959) using osmotic pressure, diffusion, and viscosity measurements. The micelles had a laminar structure with the phosphorylcholine head groups situated in the centre of the micelle, and the hydrocarbon chains extending outwards into the solvent. The micellar weight was 57,000. There are presumably repulsive forces between the polar head groups and the solvent, giving a reversal of the type of micelle structure found in water, in which the hydrocarbon chains form the interior of the micelle, and the polar groups are on the outside.As a continuation of the study of micelle formation by lecithin in organic solvents, it was decided to study lecithin in solvents which should provide intermediate conditions between water and benzene.

Cellular responses of Bacillus subtilis and Escherichia coli to the Gram stain

“…Table 2 shows the amount of phospholipid which was removed during each step of the Gram reaction. Since ethanol is a membrane perturbant (12,18) it is expected that lipid would be removed. Of the cellular lipid 30 to 43% was removed by CV, CV-I and CV-TPt without ethanol treatment.…”

“…The latter possibility would perturb the boundary water of the membrane by the dehydration effect of ethanol. Although membrane fluidity does not seem to be affected, a variety of complex alterations within and without the membrane are possible (12,16,17,18).…”

Complex formation between indole-3-acetic acid and phospholipid membrane components in aqueous media. 1. Parameters of the system

“…in CDC13 indicates that the interaction of IAA with PC is a function of micelle concentration rather than total lipid concentration. In addition, lecithin is known to form only small weak aggregates in lower alcohols like methanol (Elworthy & McIntosh, 1961) and is expected to be completely disperse in Me2SO solutions. The weak interaction parameters observed in these solvents reinforce the concept that structuring of the PC molecules into ordered aggregates is necessary for the interaction.…”

Nuclear Magnetic Relaxation and the Biological Membrane

“…In chloroform solution, lecithin exists as aggregates of 60-70 molecules (Elworthy and Macintoch, 1961). The 13C TI data for dipalmitoyl lecithin in COCl 3 (Fig.…”