Micro-Disc Electrophoresis of Brain Proteins III. Heterogenity of the nervous specific protein S-100

Abstract

The multiple forms of S-100, a protein specific of the nervous system, revealed by polyacrylamide gel micro-disc electrophoresis are caused by oxidation of this thiol-protein by ammonium persulfate, potassium ferricyanate and probably by-products of polymerization. The protein runs as a single sharp symetric fast migrating component (FMC), if no oxidizing agent or reducing agents in appropriate concentration are present in the system. Ca²⁺ does not change the single-banded pattern of the oxidizing agent free system. Depending on the ratio between protein and oxidizing agents in the gels respectively added to the system up to seven bands or a single sharp symetric slow migrating component (SMC) are formed. By fractionated extraction combining 0.01 M Tris-HCl-buffer, pH 7.4, 1.5% Triton x 100 and iso-pentanol a membrane associated protein fraction is isolated from primary water-insoluble material of brain (guinea pig) which has the same electrophoretic mobility as the oxidized form (SMC) of S-100.