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