[Heterogeneity of crystalline antithyroid phytoprecipitin].

The crystalline preparation of antithyroid phytoprecipitin has been resolved by chromatography on Whatman CM-32 cellulose on a preparative scale into two components, designed respectively A and B. Each component was further resolved into consisting polypeptide chains alpha (mol. weight 7.000) and beta (mol. weight 17.000) by gel filtration on sephadex G-50 in 1 M acetic acid 6 M urea. Homologous chains were comparatively studied by electrophoresis in acrylamide gel, amino acid analysis and peptide mapping technique. Electrophoresis in acrylamide gel with 6 M urea according to Takayama [8] revealed the identical mobility of beta chains in both components A and B, while alpha chains differed. alphaA chain was more basic, than alphaB, i.e. it had greater positive sharge. The amino acid analysis and peptide mapping showed that alphaA chain had one residue of lysine more than alphaB chain. The comparison of beta chains by peptid mapping confirmed their complete identity.