Primary structure and biological activity of hemoglobin-related hypothalamic peptides.

Five individual fractions from bovine hypothalamic extract, displaying coronary constrictory activity, were isolated and sequenced. All of them belong to the hemorphin group of hemoglobin-derived peptides. These peptides bind calmodulin and activate calmodulin-dependent enzymes. The relationship of isolated peptides with other members of the hemorphin group is discussed. Several new fragments of hemoglobin alpha- and beta-chains with yet unidentified activity were obtained from the same source. Their amino acid sequences have considerable overlap with the known sequences of hemoglobin fragments isolated from other tissues.