Effects of Sulfate Residues on the Interaction of Basic Fibroblast Growth Factor with Heparin Evaluated by Combination of Computer Modeling and Surface Plasmon Resonance methods

Abstract

Surface plasmon resonance (SPR) technology was utilized for kinetic analysis between basic fibroblast growth factor (bFGF) and heparin derivatives in order to quantitatively investigate crucial sites in the sugar chains. The strongest binary interaction was bFGF/DE-6-OS-heparin (KD=1.11nM). Affinity between N-acetyl heparin and bFGF became lower when the amino group was acetylated instead of being sulfated. KD values of bFGF/DE-2-OS- heparin, bFGF/DE-OS-heparin decreased dramatically when O- sulfates on corresponding sites were removed. This was further confirmed by a molecular modeling based on the computer modeling with SYBYL software. From the electrostatic energy Analysis, the binding energy of bFGF/heparin, bFGF/DE-OS-heparin, bFGF/N- acetyl heparin, bFGF/DE-2-OS-heparin, bFGF/DE-6-OS-heparin were -735, -547, -465, -610, -679, respectively. DE-OS-heparin. N- acetyl heparin, DE-2-OS-heparin resulted in more loss of binding capability in compared with the original heparin. It was concluded that SPR technology could be used rapidly, quantitatively, sensitively and within real time to detect molecular process of unknown complex sugar chains/growth factor interactions in combination with the computational molecular modeling in the discovering stage from the complex molecular library. Index terms: bFGF; Heparin derivatives; Kinetic Studies; Surface plasmon resonance; Molecular modeling.