Collagen-ligand interaction in dentinal adhesion: computer visualization and analysis.

The objective of this study was to characterize the interactions of selected ligand molecules with collagen structure through computer visualization of the reacting molecules and the resulting complexes. Five ligand molecules were studied. They were 2-Hydroxyethyl methacrylate, Glutaraldehyde-HEMA adduct, Glyceryl dimethacrylate, Methacryloyloxyethyl maleate and Acryloyloxyethyl citraconate. These ligands were selected with oxygen as a common heteroatom for a reactive or functional site. Energy minimized 3-D structures of the molecules were generated by Sybyl molecular modeling software. The structures were subjected to a systematic conformational search, yielding conformations of the molecules with a common recognition site with both steric and electrostatic complementarity to appropriate receptor sites in a type I collagen molecular structure. The ligands were also docked to collagen receptor by autodock procedures and the receptor sites where docking occurred were evaluated. The energy of the molecules and their complexes with collagen was evaluated and compared. The computer visualization results reveal that steric complementarity between receptor sites in collagen and optimally configured ligands may be the basis of micromechanical bonding between collagen and the ligands. Typically, ligands docked on the cavities of collagen molecular surface and wrapped around the cavities which follow the helical turns of the collagen macromolecule. In addition, analysis of electrostatic potential features revealed electrostatic complementarity as an additional source of interaction. Hydrogen bonds between ligands and collagen molecule were detected in the complexes of several of the conformations of all the ligands. Thus computer simulation studies show that steric and electrostatic complementarity and consequent interactions form the potential basis of binding between dentin adhesive ligands and type I collagen.