Thyroid-Stimulating and Lipolytic Activities of Purified Preparations of Human Thyroid-Stimulating Hormone

Abstract

A partially purified fraction of human thyroid-stimulating hormone (DEAE-II) was further purified by ion-exchange chromatography on IRC\x=req-\ 50, gel-filtration on Sephadex G-100 and finally chromatography on DEAE-cellulose. Two fractions were obtained which were high in thyroi d\x=req-\ stimulating activity (8\ m=. \ 3 and 7\ m=. \ 3 units human Research Standard A/mg) and were comparable in potency to other preparations ofthe human hormone reported in the literature. They were also electrophoretically heterogeneous as were the preparations of other workers. Lipolytic activity toward cells obtained from human or rat adipose tissue was demonstrated for all fractions containing thyroid-stimulating activity, the two activities being roughly parallel. It is concluded that both thyroid-stimulating and lipolytic activities are probably present in the same protein molecule, but it is unlikely that the latter activity is of physiological significance. buffer (pH 7-5) containing 5 mM-sodium ion (Stockell Hartree, Butt & Kirkham, 1964). After elution of the unadsorbed fraction (IRC-1) the remaining protein (fraction IRC-2) was eluted from the column with 1 M-ammonium acetate. Each fraction was concentrated by rotary evaporation, the pH adjusted to 5-5 and protein precipitated by slow addition of five volumes of 96 % (v/v) ethanol with stirring. After 2 days the protein precipitate was recovered by centrifugation, washed once with cold 96 % ethanol, twice with ethyl ether and dried in vacuo. The mean weight yield and standard deviation of the fractions in seven experiments was 50-2 + 8-6 % for fraction IRC-1 and 32-5 + 5-5% for fraction IRC-2. Since previous studies had shown that the TSH activity would be concentrated in fraction IRC-2 (Stockell Tube no.