Isolation and Properties of an Encephalitogenic Protein from Bovine, Rabbit, and Human Central Nervous System Tissue

Abstract

Abstract Sodium citrate extracts of acetone-ether-defatted rabbit, bovine, and human central nervous system tissue were chromatographed on carboxymethyl cellulose and Sephadex G-50. From each of these three tissues a protein was isolated which produced experimental allergic encephalomyelitis in 90% of recipient rabbits. The disc polyacrylamide gel electrophoretic pattern of the protein was consistent with a high degree of homogeneity. The basic amino acids constituted nearly 25% of the total. There was no half-cystine and only traces of methionine and isoleucine. Phenylalanine accounted for 90% or more of the amino-terminal amino acids, and tryptic digestion of the untreated protein gave 8 to 10 major peptide spots. The sedimentation of the protein in a 10 to 20% sucrose gradient, its elution volume from a Sephadex G-50 column, and calculations based on the results of amino acid analysis and dinitrophenylation were all consistent with a molecular weight of 4000 to 8000.