|Sulay D. Jhaveri, Harold
J. Goldston, J. Mattew Mauro, Scott A. Trammell, and Leonard M. Tender
CBMSE, Naval Research Laboratory, Washington DC, 20375, U.S.A.
Transduction of binding events at the electrode surface into changes in electrochemical signals has been the subject of several research efforts. The desired components of such electrochemical transduction systems are: affinity for the target analyte, electrochemical activity that is sensitive to changes in the micro-environment, and specificity, i.e., inhibition of nonspecific binding. I will describe the molecular engineering of a myoglobin mutant and its conversion to an electrochemical sensor for avidin. The mutant myoglobin was labeled with an environmentally sensitive, electroactive, sulfhydryl-reactive reagent, [Ru(II)(NH3)4(1,10-phenanthroline-5-maleimide)]-(PF6)2. The labeled protein was immobilized on a chemically modified gold electrode, and the exposed basic residues on the myoglobin surface were used as sites for the covalent attachment of the ligand, biotin. Binding of avidin to the ligand resulted in a change in the electrochemical signal of the redox probe, i.e., the peak current of the ruthenium complex measured by CV diminished. This system is responsive specifically to avidin and is able to quantitatively detect avidin. While the detection of avidin is merely used as a proof of principle, this type of modular approach to sensor design using the labeled myoglobin (or any other suitable protein) scaffold could potentially be used to detect any protein-ligand interaction.