Characterization of the single peptide generated from the amino-terminus end of alpha- and beta-hemoglobin chains by the Ca2+-dependent neutral proteinase.
Human erythrocyte Ca2+-dependent neutral proteinase catalyzes a limited proteolysis of isolated globin chains. The rate of hydrolysis is very rapid using heme-deprived alpha- or beta-globin chains and is reduced to one-fifth with their corresponding native forms. In both cases, the proteinase specifically cleaves a single peptide bond, this resulting in the removal from the amino-terminus end of an octapeptide in beta-globin and of an undecapeptide in alpha-globin. Both peptides have been isolated, their amino acid composition has been characterized and the susceptible site of cleavage has been identified. Hemoglobin variants show a different rate of digestion as compared to that of normal chains. The alpha-Hasharon [alpha 47(CE5) Asp----His] undergoes rapid digestion, while the beta-G San Josè chain [beta 7(A4) Glu----Gly], which carries the mutation near the site of cleavage, reveals a high degree of resistance to proteolytic degradation by the neutral proteinase.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002154:Calpain; D010450:Endopeptidases / Q000097:blood*; D005914:Globins / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D006455:Hemoglobins, Abnormal / Q000378:metabolism; D006801:Humans; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism*; D013379:Substrate Specificity
D000596:Amino Acids; D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D010446:Peptide Fragments; C029985:hemoglobin Sealy; D005914:Globins; C032126:hemoglobin G San Jose; D010450:Endopeptidases; D002154:Calpain