title: Purification and characterization of the seven cyanogen bromide fragments of human serum transferrin.
abstract: 1. Procedures are described for the isolation of seven distinct cyanogen bromide fragments in high yield from human serum transferrin. 2. Cyanogen bromide-cleaved transferrin is separated into three fragments (CN-A, CN-B and CN-C) by gel filtration with Sephadex G-100. 3. Four peptides are obtained from CN-A (the largest fragment) after reduction and carboxamidomethylation, by gel filtration in acidic solvents. Two peptides are similarly obtained from fragment CN-B, whereas fragment CN-C is a single cystine-free peptide. 4. The molecular weights of the seven peptides, as determined by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, by sedimentation-equilibrium ultracentrifugation and by sequence studies, range from 3100 to 27000. Together they account for a molecular weight of 76200 for transferrin. 5. The two largest fragments contain the carbohydrate attachment sites of the protein, and the smallest fragment is derived from the N-terminus. 6. The amino acid compositions and N-terminal groups of the fragments are reported and the results compared with those of previous investigations.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002499:Centrifugation, Density Gradient; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D014168:Transferrin / Q000032:analysis
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D014168:Transferrin; D003488:Cyanogen Bromide