DISULPHIDE BRIDGES AND IMMUNOCHEMICAL PROPERTIES OF YOSHIDA ASCITES TUMOR AND NORMAL SERUM GLYCOPROTEIN

1. 1.|Different procedures have been applied for the partial and full reduction of the glycoproteins isolated from Yoshida ascites tumor and from normal serum. 2. 2.|Neither glycoprotein possesses free reactive or unreactive SH groups. They are therefore disulphide proteins. 3. 3.|Reduction with mercaptoethanol, even if extensively carried out and followed by alkylation, was never complete, when the lower number of titrated SH groups was used as criterion. 4. 4.|The quantitative reduction of disulphide bonds has been achieved by reaction with sulphite, and the sulphydryl groups have been spectrophotometrically titrated with p-hydroxymercuribenzoate. The presence of 4 disulphide bridges in the Yoshida glycoprotein and 10 in the normal serum glycoprotein has been ascertained. 5. 5.|The relation between the reductive cleavage of S:S bonds and the antigenicity of both glycoproteins has been studied. Both molecules lost their antibody-precipitating capacity after the opening of more than one disulphide bridge. © 1969.