STUDIES ON THE NATURE OF CORTICOTROPHIN RELEASING HORMONE AND ITS PARTIAL PURIFICATION FROM PORCINE HYPOTHALAMI

Abstract

Partially purified CRH [corticotropin-releasing hormone] was subjected to chromatography on Sephadex G-50 under various conditions. The results throw some light on the nature of CRH and provide a procedure for its large scale purification. Isolated pituitary cell suspensions prepared by collagenase disaggregation of rat adenohypophysis were used to assay CRH. In a typical extraction, CRH activity was detected at both the void and total column volumes (implying approximate MW of 30,000 and 1500, respectively), suggesting that the low molecular weight activity might represent free CRH, while the higher molecular weight material might be associated with aggregated forms. To investigate this hypothesis, profiles of CRH eluted from Sephadex G-50 in both a strongly ionic and a strongly hydrophobic eluent were examined. Hydrophobic interactions are apparently most important, since the elution in the presence of 15% (vol/vol) dimethyl formamide (which lessens such interactions), resolves the CRH into essentially 1 peak of material which has a MW less than 1500.