Identification of hemorphins in a cathepsin D bovine hemoglobin hydrolysate by radioimmunoassay and photodiode array detections

Morphinomimetic peptides have been purified from hemoglobin enzymatic hydrolysates and a significant amount of evidence has been accumulated indicating that the generation of these peptides (hemorphins) might occur in vivo. In order to investigate their putative physiological role and processing from hemoglobin in vivo, two methods were developed: a specific radioimmunoassay and a UV spectra comparison analysis. These methods were applied to a cathepsin D bovine hemoglobin hydrolysate and allowed the detection of two hemorphin-7 peptides. This observation supports the putative implication of cathepsin D in the in vivo release of hemorphins. Among the two methods used in this study, the immunological approach exhibits higher sensitivity and represents a useful method to investigate the in vivo role and physiological processing of hemorphins.