甲状腺腫よう内ｔｈｙｒｏｇｌｏｂｕｌｉｎの生化学的検討

Abstract

Glycoproteins in human thyroid tumors were fractionated by affinity chromatography in a concanavalin A (ConA)-Sepharose 4B column. Anti-human Tg (thyroglobulin; 660kDa glycoprotein consisting of 10% carbohydrate) antibody-Sepharose 4B affinity chromatography was performed on the fractions which were bound or not bound to ConA. Tgs which were purified from each fraction were subjected to wheat germ agglutinin (WGA) affinity electrophoresis, and their characteristics with respect to the structural changes of their carbohydrate chains were studied. Human Tg, purified by the HPLC system, was used to immunize rabbits. Anti-human Tg antibody was purified from rabbit anti-serum with the use of sodium sulfate. Following are the characteristics of Tg in thyroid adenoma: (I) Tg which was dissociated into 12S subunits due to the definitely decreased iodine content of Tg in tumor tissue, was present in the fraction bound to ConA. (II) When ConA-Sepharose 4B affinity chromatography was performed by linear gradient elution with 0-500mM methyl-α-D-mannopyranoside (MeM), the fraction which was eluted with 0-200mM MeM contained most of Tg which had been dissociated into 12S subunits. (III) Tg which was eluted with 0-200mM MeM had a strong affinity for WGA. (IV) Tg which was eluted with 200-500mM MeM showed no affinity for WGA. (V) Tg which was not bound to ConA showed a relatively strong affinity for WGA. (VI) It appeared that Tg preparation mentioned in (V) was 19STg and its dimer, and Tg which was dissociated into 12S subunits could not be found in the fraction not bound to ConA. Tg not bound to ConA had a higher iodine content than Tg bound to ConA.