Human pituitary thyrotropin. Characterization of five glycoproteins with thyrotropin activity.

Human pituitary thyrotropin prepared by chromatography on hydroxyapatite or on SP-Sephadex was fractionated into five active components by preparative poly-acrylamide gel electrophoresis. The potency of the five components was 4-9 units human Research Standard A/mg. Examination of the components by analytical electrophoresis and by immunological methods revealed no heterogeneity. Ultracentrifugaiton of the three major components showed homogeneity with sedimentaiton coefficinets in the range of 2.4-3.0 S and a value for the molecular weight of about 33 000. Amino acid and carbohydrate analyses indicated close similarites between the five components.