PMID: 19017259

 

    Legend: Sugar

Title : Biochemical characterization of plasma-derived tissue factor pathway inhibitor : post-translational modification of free, full-length form with particular reference to the sugar chain

Abstract :
  1. BACKGROUND: Tissue factor pathway inhibitor ( TFPI ) is a physiological protease inhibitor that inhibits the initial reactions of the extrinsic blood coagulation pathway
  2. Most TFPI in human plasma is associated with lipo proteins ; however, the most functionally active form is thought to be the free, full-length form (f-p TFPI )
  3. Cell culture derived TFPI and recombinant TFPI ( rTFPI ) exhibit variations in their respective anticoagulant activity, which may be caused by post-translational modifications, such as the frequent differences in sugar chain structures among recombinant proteins
  4. Sugar chain structures in rTFPI expressed in Chinese hamster ovary (CHO) cells have been reported previously, but those of plasma TFPI have not been
  5. OBJECTIVES: To purify f-p TFPI and analyze the sugar chain structures
  6. RESULTS AND CONCLUSION: f-p TFPI was purified to homogeneity from blood plasma using a combination of anion-exchange, heparin affinity, immunoaffinity, and reversed-phase chromatographies, resulting in a yield of 76%
  7. f-p TFPI showed a partially phosphorylated glycoprotein comprising a total of 276 amino acids by peptide mapping
  8. The sugar chain structures were analyzed by two-dimensional sugar mapping combined with exoglycosidase digestion of the pyridylamino sugar chains and the following results were obtained
  9. (Sialyl) Galbeta1-3GalNAc was linked to Thr(175) , partially to Thr(14) and Ser(174) ; sialyl complex-type sugar chains to Asn(117) and Asn(167) , whereas Asn(228) was not glycosylated
  10. Neuraminidase-resistant acidic sugar chains including sulfated sugar chains were not observed significantly
  11. The protease inhibitory activities of f-pTFPI towards activated factor (F) X and tissue factor-activated FVII complex were identical to those of full-length rTFPI expressed in CHO cells