The application of counter-current methods to the fractionation of lipid material from brain.

The fractionation of lipid mixtures by classical methods based on their differential solubilities in organic solvents is an elaborate and lengthy procedure, frequently yielding products of doubtful purity. For this reason alternative methods of purification were sought. Attempts to apply adsorption chromatography were not encouraging in our hands, as the separation was poor, and invariably about 25% of the material remained firmly adsorbed to the column, resisting elution by all the usual solvents. Partition chromatography on silica gel was unsatisfactory, as the phospholipins altered the equilibrium between stationary and mobile phases, and completely upset the columns. Separation of lipids by the methods of countercurrent distribution (Craig, 1944, 1950) seemed to avoid these difficulties. Partition between solvents is not complicated by a supporting medium. Recently, Lovem (1952) has applied the countercurrent method to the fractionation of brain phospholipins. The investigations reported here cover the development of a basic solvent system for the distribution of brain lecithin, kephalin, and mixed sphingomyelin and cerebrosides. This solvent system was then applied to the distribution of crude brain lipid, and modified for the study of certain fractions. The identity ofthe fractions obtained was then sought by various analytical methods, and from these results the positions of some of the more clearly defined lipids in the distributions have been indicated. Part of this work has been presented at a meeting of the Biochemical Society on 24 October 1952 (Cole, Lathe & Ruthven, 1953a).