Significant CRF activity was found in a fraction with R(f) = 0.82-0.7 or V(E)/V(T) = 0.41-0.48 obtained by gel filtration of acid extracts of pig hypothalami on Sephadex G-25. The activity of this fraction decreased markedly during subsequent purification, particularly in the last two steps. From this fraction, a heptapeptide with significant ACTH releasing activity in vitro, was isolated in pure state, and its amino acid sequence was established as H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH. This heptapeptide was synthesized by solid phase methods. The CRF activity of synthetic heptapeptide in vitro was low but could be potentiated by a cofactor fraction from rat hypothalamic extract.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical