Separation of Cerebroproteins of Human Brain

Abstract

THE correlation of protein chemistry with complex functions of the brain has been hampered by the lack of basic information on the brain proteins. Extraction of brain proteins by techniques available so far has yielded usually less than 20 per cent of the total protein content of brain, and only up to 14 components have been demonstrable by electrophoresis¹. Recent work in this laboratory has been directed to the definition of more quantitative methods for the extraction of brain proteins and for more adequate separation, physicochemical characterization, and histological localization by immunochemical methods². We have observed that through a combination of mild buffered extraction, column chromatography on DEAE-cellulose and analysis of the carbohydrate content of each effluent tube, the presence of not less than 50 major chromatographic fractions can be distinguished (Fig. 1). Acrylamide gel-electrophoresis of each of these major fractions shows each to be heterogeneous. Accounting for overlap between chromatographic fractions, a minimum of 100 cerebroproteins from human grey matter have thus been observed. The total yield of protein in these experiments is 6.1 g/100 g wet wt. grey matter—a figure in range for previous figures for total unfractionated brain protein³. The previously known partially characterized protein fractions of brain¹, together with the contribution by serum proteins from blood remaining in small vessels of grey matter, are not likely to account for more than a small percentage of this total yield. Thus, the bulk of the proteins here demonstrated apparently have not been separated or examined previously.