Abstract
MSH-release inhibiting hormone (MRIH) activity in bovine hypothalamic extracts, concentrated over 11,000-fold by gel filtration on Sephadex, was further purified by thin-layer chromatography. Two MRIH-active peptides were isolated; one showed a high and the other much weaker MRIH activity. The amino acid sequence of the main MRIH-active peptide, as determined by Edman degradation combined with the dansyl method, was shown to be prolyl-leucyl-glycine amide. These findings were confirmed by mass spectra. Synthetic L-Pro-L-Leu-glycine amide and the natural main MRIH-active peptide showed similar biological activities, chromatographic and electrophoretic mobilities, and mass spectral fragmentation patterns. This work indicates that the structure of bovine MRIH is L-Pro-L-Leu-Gly. NH
2.
