title: Location of the disulfide bonds in human coagulation factor XI: the presence of tandem apple domains.
abstract: Factor XI is a plasma glycoprotein that participates in the blood coagulation cascade. Of the 19 disulfide bonds present in each of the subunits of the human protein, 16 were determined by amino acid sequence analysis of peptide fragments produced by chemical and enzymatic digestion. Four apple domains of 90 or 91 amino acids were identified in the tandem repeats present in the amino-terminal portion of each subunit of factor XI. The disulfide bonds in the carboxyl-terminal portion of the molecule were similar to those in the catalytic region of other serine proteases. The two identical subunits of factor XI were connected by a single disulfide bond at Cys321 linking each of the fourth apple domains while each of the Cys residues at position 11 in the first apple domains forms a disulfide bond with another Cys residue.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle 98195.
authors.forename: B A
authors.initials: BA
authors.lastname: McMullen
authors.forename: K
authors.initials: K
authors.lastname: Fujikawa
authors.forename: E W
authors.initials: EW
authors.lastname: Davie
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D004220:Disulfides / Q000032:analysis; D005172:Factor XI / Q000737:chemistry* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D011487:Protein Conformation; D014357:Trypsin
chemical_list: D004220:Disulfides; D010446:Peptide Fragments; D005172:Factor XI; D014357:Trypsin; D003488:Cyanogen Bromide