Peptic hemoglobin hydrolysis in an ultrafiltration reactor at pilot plant scale generates opioid peptides

Two hemorphins, peptides with opioid activity, have been isolated from a pepsin hydrolysate of bovine hemoglobin, by use of gel permeation (GP) and reverse phase (RP) high-performance liquid chromatography (HPLC). Their primary structure and accurate molecular weights, determined by amino acid analysis and fast atom bombardment (FAB) mass spectrometry, were identical to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin 7) of the beta-chain of bovine hemoglobin. Two other peptides, 34-40 (hemorphin-7) and 34-41 (hemorphin-8) of the beta-chain of bovine hemoglobin, have been synthesized and studied. The opioid potency of these peptides, exhibited by the use of electrically stimulated muscle of isolated guinea pig ileum (GPI), were significant and comparable with some others previously described. Studies of opioid activities and primary structure of hemorphins led us to postulate the important role of arginine and phenylalanine in opioid potency.