Purification of an organ-specific thermostable antigen found in bovine brain.

Investigations were carried out in order to isolate the brain-specific antigen found in BE preparations of bovine brain. Ammonium sulphate fractionation indicated that this thermostable brain-specific activity was found primarily in the fraction precipitating between 0.00 and 2.00 M concentrations, and more probably, at concentrations between 0.00 and 1.50 M. The brain-specific antigen was better purified by means of column chromatography on DEAE-cellulose. It was eluted primarily with 0.25 M sodium phosphate buffer of pH 5.00, in a fraction designated as peak four. This component exhibits ultracentrifugal and electrophoretic homogeneity and is considerably enriched in the specific antigenic activity. This brain-specific component was found to be present in the slowest of the ultracentrifugal peaks seen in the crude preparation; it has a sedimentation coefficient of about 1.8S. Direct chemical analysis showed that this antigen is a kind of glycoprotein.