The localization of the basic protein and N-2 in diseased myelin.

A non-penetrating reagent 4,4'-diisothiocyano-2,2'-ditritiostilbene disulfonic acid ([3H]DIDS) has been used to label isolated normal and diseased myelin. The basic protein and the hydrophobic protein, N-2, were isolated from each myelin. When normal myelin was labeled the specific activity of the basic protein was about 25% of that of the hydrophobic protein (N-2). The specific activities of these two proteins isolated from chronic multiple sclerosis myelin were similar to those of the normal myelin. In contrast, the specific acitivity of the basic protein isolated from acute multiple sclerosis myelin was about 400% higher than that of the basic protein isolated from either normal or chronic multiple sclerosis myelins. The specific activity of the N-2 protein was only 50% of that of the N-2 protein isolated from normal and chronic multiple sclerosis myelins. It was concluded that the arrangement of proteins in isolated chronic multiple scerosis myelin was not markedly altered in comparison to that of isolated normal myelin. However, the arrangement of proteins in acute multiple sclerosis myelin appeared to be considerably different from that of the other two myelins.