Detection of low affinity interactions between peptides and heat shock proteins by chemiluminescence of enhanced avidity reactions (CLEAR).

Protein-protein and protein-peptide interactions that are low affinity in nature preclude the straightforward measurement of binding. To overcome this limitation, a novel method has been devised for stabilizing these weak interactions by increasing the binding avidity. These studies have focused on the binding of peptides to heat shock proteins (with a typical KD of approximately 25 to 50 microM). Multivalent ligands have been created by coupling peptides plus biotin to a neutral carrier molecule, dextran. These peptide-dextran conjugates allow for more avid binding to proteins that have been immobilized on a membrane surface. Detection of signals via enhanced chemiluminescence further increases the sensitivity of the method that has been termed Chemiluminescence of Enhanced Avidity Reactions (CLEAR). The assay is simple, reliable and consistently detects specific binding between heat shock proteins and peptide ligands. CLEAR should be generally applicable to other ligand receptor pairs where the detection of binding is limited by the low affinity of the interaction.