抄録
An attempt was made to separate the LATS from human thyrotropin which was added to the hyperthyroid serum using the gel filtration on Sepadex G 200. The dextran gel “Sephadex G 200” was allowed to swell overnight in a buffer solution (0.01 M Tris-HCl in 0.02 M NaCl, pH 8. 6), and packed into a 2×40 cm. column. As shown in Fig. 1, four fractions were obtained. LATS was found in Fraction 2 (which contained 20-30% by weight of the original serum protein) and thyrotropin was found in Fraction 3. However, the separation of each thyroid stimulating substance in serum was not complete. A small amount of thyrotropin contaminated Fraction 2 because the TSH activity in Fraction 2 was reduced when neutralized by rabbit anti TSH (bovine) -serum. (Table 1.)
At the second step, rechromatography of Fraction 2 on Sephadex G 200 was performed using DEAE derivative of cross-linked dextran (DEAE-Sephadex A 25, 3.2 meq/ N/g). As shown in Fig. 2, LATS activity was observed in both the first and second fractions. However, thyrotropin was completely absorbed on DEAE-Sephadex (Table 2).
The weight of serum protein in the first and second fractions totaled 10.9% of the original protein.
No inhibition of LATS activity was observed after adding antiserum to the fractions obtained. From this result, it can be said that the LATS was almost completely separated by the two steps : Gel filtration on Sephadex G 200 and rechromatography of the second fraction on DEAE-Sephadex A 25.
Furthermore, it became clear that there are both LATS and thyrotropin in some hyperthyroid sera in which the 2-hour response is suppressed by the addition of the antiserum and the response curve changes to the prolonged type. This was also proved by the separation of LATS and thyrotropin in case 4.
