During the development of a method for the extraction and purification of lipids from central nervous system (Folch et al., 1951), it was observed that a chloroform: methanol 2:1 mixture, v/v, (CM) extracted from central nervous system some protein material (Folch and Lees, 1951). This material was not removed from the extract upon repeated washing with water. Its presence in the extract was revealed by the fact that when the extract was taken to dryness by evaporation of the solvents, the resulting residue proved to be only partly soluble in the chloroform: methanol mixture that had been used in the original extraction of the tissue. The portion of the residue that was insoluble in CM, was found also to be insoluble in water, and in all of a large number of aqueous solutions and organic solvents that were tested. The insoluble material contained 14% N, 1.76% S and between 0.2% and 0.4% P. Upon adequate acid hydrolysis, over 91% of its N could be recovered chromatographically as free amino acids, i.e., the insoluble material was mainly protein in nature.
KeywordsWhite Matter Amino Acid Composition Silicic Acid Myelin Protein Methanol Mixture
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