Properties of the four purified components of whale thyroid-stimulating hormone (TSH) have been compared. The amino acid composition shows close similarity among these components. Their hexosamine and sialic acid contents are of the same magnitude, whereas the neutral sugar composition differs somewhat from each other. The molecular weight of whale TSH determined by sedimentation equilibrium is 29,000, and no difference in molecular weight as well as in Stokes radius as determined by gel filtration has been detected among these four components. The amino acid and carbohydrate compositions of whale TSH resemble those of TSH from other species, especially those of non-primate mammalian TSH. Whale TSH contains, unlike bovine TSH but like human TSH, 1-2 residues of sialic acid as a constituent carbohydrate.
Affinity chromatography on a concanavalin A (con A)-Sepharose column is a potentially useful for the isolation of whole thyroglobulin (Tg) at least from normal thyroid tissue. In addition to being a simple procedure for the isolation of Tg, large amounts of Tg can be applied to the column and recovered in good yield with a buffer containing MeG. In gradient elution with buffer containing increasing amounts of MeG, a single but broad peak was obtained, without separation into subfractions. However, a hemagglutination-inhibition test showed that the Tg preparation eluted early from the column had less affinity for con A than the Tg preparation eluted later, suggesting a heterogeneous distribution of carbohydrate moieties among Tg preparations. When human Tg from thyroid tumor was applied to the column, tumor Tg partly passed through the column without being adsorbed. This unadsorbed Tg showed a very low affinity for lectins, con A and wheat germ agglutinin (WGA), as determined by a double diffusion reaction in agar gel. In contrast to this fraction, the Tg adsorbed on the con A-gel column showed a very strong affinity for WGA, differing from Tg of normal thyroid tissue. Therefore, tumor Tg preparation appears to have an abnormally modified carbohydrate structure, at least in part. The higher affinity for WGA (with a specificity for N-acetylglucosamine) seen in adsorbed Tg could be due to a larger amount of GlcNAc residues which bind irregularly in the carbohydrate moiety of tumor Tg.
Abstract The aggregation reaction of histone I, i. e., the main fraction of calf thymushistone, was studied by means of sedimentation, diffusion, viscosity measurement and electrophoresis. The aggregation was found to proceed usually at a temperature higher than 20°C, although it occurred at pH’s above 7 even at 0°C. High temperature, pH, ionic strength or protein concentration promoted the reaction. It was also found that sulfate ion was an effective aggregating agent. The aggregation was not reversed by lowering the temperature, but disaggregation occurred when the ionic strength of the solution containing the aggregate was reduced by dialysis. The aggregate was rather large in size. It consisted of about 30 molecules of his-tone I under certain aging conditions (pH 5.0) and had nearly the same frictional ratio as that of the monomer. Electro-phoretic mobility slightly increased with aggregation at pH 5.0. On the basis of the data presented, a possible mechanism in forming the aggregate was discussed.
