PMID: 1904059

 

    Legend: Sugar

Title : Human plasma and recombinant factor VII

Abstract :
  1. Characterization of O-glycosylations at serine residues 52 and 60 and effects of site-directed mutagenesis of serine 52 to alanine
  2. Factor VII is a multidomain , vitamin K-dependent plasma glycoprotein that participates in the extrinsic pathway of blood coagulation
  3. Earlier studies demonstrated a novel disaccharide (Xyl-Glc) or trisaccharide (Xyl2-Glc) O-glycosidically linked to serine 52 in human plasma factor VII (Nishimura, H., Kawabata, S., Kisiel, W., Hase, S., Ikenaka, T., Shimonishi, Y., and Iwanaga, S. (1989) J. Biol
  4. Chem
  5. 264, 20320-20325)
  6. In the present study, human plasma and recombinant factor VII were isolated and subjected to enzymatic fragmentation
  7. Peptides comprising residues 48-62 of the first epidermal growth factor-like domain of each factor VII preparation were isolated for comparative analysis
  8. Using a combined strategy of amino acid sequencing, carbohydrate and amino acid com position analysis, and mass spectrometry, three different glycan structures consisting of either glucose, glucose-xylose, or glucose-(xylose)2 were detected O-glycosidically linked to serine 52 in plasma and recombinant factor VII
  9. Approximately equal amounts of the three glycan structures were observed in plasma factor VII , whereas in recombinant factor VII the glucose and the glucose-(xylose)2 structures predominated
  10. In addition to the O-linked glycan structures observed at serine 52 , a single fucose was found to be covalently linked at serine 60 in both human plasma and recombinant factor VII
  11. Carbohydrate and mass spectrometry analyses indicated that the fucosylation of serine 60 was virtually quantitative
  12. Metabolic labeling studies using [14C]fucose confirmed the presence of O-linked fucose at serine 60
  13. In order to assess whether the carbohydrate moiety at serine 52 contributes to the biological activity of factor VII , we have constructed a site-specific mutant of recombinant factor VII in which serine 52 has been replaced with an alanine residue
  14. Mutant factor VIIa exhibited approximately 60% of the coagulant activity of wild-type factor VIIa in a clotting assay
  15. The amidolytic activity of mutant factor VIIa was indistinguishable from that observed for recombinant wild-type factor VIIa
  16. In addition, the ability of mutant factor VIIa in complex with either purified relipidated tissue factor apoprotein or tissue factor on the surface of a human bladder carcinoma cell line (J82) to activate either factor X or factor IX was virtually identical to that observed for wild-type factor VIIa
  17. These results indicate that the carbohydrate moiety O-glycosidically linked to serine 52 does not appear to be involved either in the interaction of factor VIIa with tissue factor , or the expression of its proteolytic activity toward factor X or factor IX following complex formation with tissue factor
  18. (ABSTRACT TRUNCATED AT 400 WORDS