Surface plasmon resonance analysis of ricin binding to plasma membranes isolated from NIH 3T3 cells

As the potential for bioterrorism has appeared to increase, the need for simple systems for identifying potential inhibitors of the binding of such biological agents to cell membranes has increased. In this work, surface plasmon resonance (SPR) was used to monitor binding of ricin, a ribosome-inactivating protein, to the plasma membranes of NIH 3T3 cells. Once conditions were established, efficacy of the system for monitoring effectiveness of compounds at inhibiting ricin binding was ascertained by determining the IC₅₀ values for asialofetuin (ASF) and for bovine serum albumin derivatized with an average of 34 lactosyl moieties (BSA-Lac₃₄). Results indicated that SPR is an efficient method for measuring adherence of a toxin to isolated cell plasma membranes. SPR can also indicate whether a compound that is an effective inhibitor of binding when a single ligand such as ASF is used will be as effective when used in studies with cells that may express multiple cell surface ligands for ricin and/or the inhibitor.