RESUMO
Cyanogen bromide digestion of hemopexin at its 6 methionine residues results in 7 fragments (CB1-CB7) partially connected by disulfide bridges. By sequence studies of fragments CB1-CB4 and peptides prepared by their enzyme cleavage, a continuous amino acid sequence of the N-terminal region of human hemopexin, comprising 220 amino acid residues, was determined. The presence of intramolecular disulfide bonds, connecting half-cystine residues 126/130 and 165/170, was proved in fragments CB2 and CB3. Fragments CB1-CB4 include 5 sites, where hexosamine oligosaccharides are attached (positions 1,41,164,217 and probably 223). In the sequenced region two sites sensitive to acid hydrolysis--bonds ... Asp--Pro ... in positions 20/21 and 187/188 were found. In spite of the fact that pooled material of many donors was studied, no sequence heterogeneity was discovered.
