AMINO-ACID SEQUENCE STUDIES ON THE ALPHA-CHAIN OF HUMAN-FIBRINOGEN - OVERLAPPING SEQUENCES PROVIDING THE COMPLETE SEQUENCE

The complete amino acid sequence of the α chain of human fibrinogen has been determined. It contains 610 amino acid residues and has a calculated molecular weight of 66124. The chain has 10 methionines, and fragmentation with cyanogen bromide yields 11 peptides [Doolittle, R. F., Cassman, K. G., Cottrell, B. A., Friezner, S. J., Hucko, J. T„ & Takagi, T. (1977) Biochemistry 16, 1703], The arrangement of the 11 fragments was determined by the isolation of peptide overlaps from plasmic and staphylococcal protease digests of fibrinogen and/or α chains. In addition, certain of the cyan ogen bromide fragments, preliminary reports of whose sequences have appeared previously, have been reexamined in order to resolve several discrepancies. The α chain is homologous with the β and γ chains of fibrinogen, although a large repetitive segment of unusual composition is absent from the latter two chains. The existence of this unusual segment divides the sequence of the α chain into three zones of about 200 residues each that are readily distinguishable on the basis of amino acid composition alone. © 1979, American Chemical Society. All rights reserved.