Purification of human thyroglobulin for radioimmunoassay and testing by ultracentrifugal analysis and immunoelectrophoresis

Abstract

The development of sensitive radioimmunoassays for the measurement of thyroglobulin (Tg) in human serum has demanded a high degree of purity of the Tg preparation. A procedure for purification of Tg including immunological methods for both purification and control of purity was therefore used. Extract of human thyroid glandular tissue from a patient with Grave's disease was chromatographed on Sepharose CL6B and subsequently on an affinity column containing antibody to whole human serum. Control of both purification steps was by fused rocket electrophoresis of fractions and crossed immunoelectrophoresis of the concentrated solutions. It could thus be shown that traces of contaminating serum proteins, present after column chromatography, were removed by affinity chromatography. Ultracentrifugation of 125I-labelled Tg indicated that it had a sedimentation rate corresponding to 19 S.