[Several properties of one of the acid neurospecific antigens].

The identity of one of the acid neurospecific antigens (antigen A) and S-100 protein has been established through agar gel immunoelectrophoresis and Sephadex G-100 gelchromatography. On agar gel electrophoresis antigen A moves as 2 fractions which occupy positions of blood serum prealbumins and alpha2 globulins. Both fractions of the antigen have a molecular weight of 25000. The heterogenic nature of antigen A (protein S-100) during electrophoresis on agar gel is discussed.