Differential binding of low molecular weight heparins with antithrombin and platelet factor 4 as measured by surface enhanced laser desorption ionization (SELDI)

Abstract

IntroductionHeparin (H) and low molecular weight heparins (LMWHs) are composed of multiple chain components varying in their physicochemical and biologic profile. LMWHs are derived by depolymerization of heparin and differ in their composition and biologic profiles. Antithrombin (AT) and platelet factor 4 (PF4) represent two of the major modulators of heparin oligosaccharides. Protein chip array technology is useful in the binding of proteins to various ligands. In this study SELDI is utilized to investigate the differential binding of H and various LMWHs.Materials and methodsH and various branded LMWHs such as Enoxaparin, Dalteparin, Tinzaparin and generic versions of Enoxaparin were studied for their complexation with purified human AT and PF4. All agents were mixed in Tris HCl buffer matrix at equigravimetric amounts. Gold chips were employed to determine the molecular profile and the binding ratios were determined by measuring peak intensities. The relative suppression of peak intensities were proportional to the binding profile of each of these agents.ResultsFor both the AT and PF4 binding on a gravimetric basis, H was found to bind much higher than the LMWHs. Significant differences in the binding profiles for the AT and PF4 were noted among different LMWHs. These binding differences may be due to the compositional differences in these drugs.