UNDERSTANDING INTERCELLULAR INTERACTIONS AND CELL-ADHESION - LESSONS FROM STUDIES ON PROTEIN-METAL INTERACTIONS

To understand cell-cell interactions and the interactions of cells to non-biological materials, studies on binding forces between cellular p roteins and between proteins and non-biological material such as metal surfaces are essential. The adsorption of proteins to solid-water int erfaces is a multifactorial and a multistep process. First steps are d etermined by long-range interactions where surface properties such as hydrophobicity, distribution of charged groups, ion concentrations and pH play important roles. In later steps structural rearrangements in the protein molecule and dehydration effects become more important mak ing the adsorption process often irreversible. In the following we dem onstrate that protein A and tubulin have a specific type of interactio n to metal surfaces probably as an intermediate step in the adsorption process. The proteins were attached to the tip of a microfabricated c antilever in such a way that only one molecule interacts with the surf ace. By recording force-distance curves with an atomic force microscop e the adhesion forces of single molecules binding to gold, titanium an d indium-tinoxid surfaces were measured. (C) 1997 Academic Press.