Blood clotting factor IX Niigata: substitution of alanine-390 by valine in the catalytic domain

J Biochem. 1988 Dec;104(6):878-80. doi: 10.1093/oxfordjournals.jbchem.a122575.


Factor IX Niigata is a mutant factor IX responsible for the moderately severe hemophilia B in a patient who has a normal level of factor IX antigen with reduced clotting activity (1-4% of normal). We reported previously that the purified mutant protein could be converted to the factor IXa beta form by factor XIa/Ca2+ at a rate similar to that in the case of normal factor IX, but the resulting mutant factor IXa beta could not activate factor X in the presence of factor VIII, Ca2+, and phospholipids (Yoshioka, A. et al. (1986) Thromb. Res. 42, 595-604). In the present study, we analyzed factor IX Niigata at the structural level to elucidate the molecular abnormality responsible for the loss of clotting activity. Amino acid sequence analysis of a peptide obtained on lysyl endopeptidase digestion, coupled with subsequent SP-V8 digestion, demonstrated that the alanine at position 390 was substituted by valine in the catalytic domain of the factor IX Niigata molecule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine
  • Amino Acid Sequence
  • Binding Sites
  • Factor IX* / genetics
  • Factor IX* / isolation & purification
  • Hemophilia B / blood*
  • Hemophilia B / genetics
  • Humans
  • Molecular Sequence Data
  • Mutation
  • Peptide Fragments / isolation & purification
  • Valine


  • Peptide Fragments
  • factor IX Niigata
  • Factor IX
  • Valine
  • Alanine