STRUCTURAL REQUIREMENTS OF HUMAN TISSUE FACTOR PATHWAY INHIBITOR (TFPI) AND HEPARIN FOR TFPI-HEPARIN INTERACTION

Heparin affinity chromatography of synthetic peptide fragments mimicki ng tissue factor pathway inhibitor (TFPI) indicated that the minimal h eparin binding sequence consists of 12 amino acid residues located at the C-terminal tail. Within this minimal sequence, Arg-257 and Arg-259 appeared to contribute most significantly to interaction with heparin . Affinity chromatography of TFPI using immobilized heparin derivative s regiospecifically desulfated at 0-6 of the glucosamine residue, N-2 of the glucosamine residue, and/or 0-2 of the iduronic acid residue in dicated that all the sulfate groups in heparin appeared to be required for TFPI-heparin interaction. Among them, however, the 6-O-sulfate gr oups appeared to make the largest contribution to the interaction, whi le the 2-O-sulfate groups contributed the least. In vitro experiments on the inhibition of factor Xa by TFPI enhanced with native and chemic ally modified heparins afforded similar results. (C) 1998 Elsevier Sci ence Ltd.