Characterization of corticotropin-releasing factor activity from sheep hypothalamic extracts

Sheep hypothalamic extracts, chromatographed on Sephadex G-25, revealed 3 peaks with CRF biological activity. The first eluting peak co-chromatographed with ACTH. After separation from ACTH by CMC, this CRF peak contained vasopressin immunoactivity and pressor activity. The second eluting CRF peak also contained vasopressin immunoactivity and pressor activity and was found to represent the presumed authentic vasopressin. The third eluting CRF peak contained vasopressin immunoactivity but no pressor activity. Further processing of this putative CRF on Sephadex G-10 resulted in a 500-fold purification. The material is inactivated by proteolytic enzymes. We tentatively conclude that this CRF is a peptide with a molecular weight of 700–1000 and that it shares common antigenic determinants with vasopressin.