PROTEOLYTIC DEGRADATION OF HEMOGLOBIN IN ERYTHROCYTES YIELDS BIOLOGICALLY-ACTIVE PEPTIDES

The formation of biologically active hemoglobin fragments in human ery throcytes was studied. The structures of 33 peptide products of intrae rythrocytic hemoglobin cleavage were determined. Based on an analysis of these sequences, a model of the stepwise degradation of the hemoglo bin alpha- and beta-chains was suggested. The processes of peptide for mation in a cell-free erythrocyte lysate system were studied. The invo lvement of an enzymatic complex of the cell membrane fraction was demo nstrated. It was found that the cells of a surviving human erythrocyte culture secrete short (of 5-20 amino acid residues) peptides, and the structures of 36 peptides were determined. The dynamics of peptide se cretion was investigated, and preliminary data on the energy-dependenc e of this process were obtained. Based on the experimental results, a model describing erythrocytes as an endocrine gland was suggested.