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Title: UNEXPECTED RETENTION OF ELECTROSTATICALLY ADSORBED CYTOCHROME C IN HIGH IONIC STRENGTH SOLUTIONS

Author
item Dicarlo, Cory
item Compton, David - Dave

Submitted to: Journal of the Chemical Society Chemical Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2004
Publication Date: 1/4/2005
Citation: DiCarlo, C.M., Compton, D.L. 2005. Unexpected retention of electrostatically adsorbed cytochrome c in high ionic strength solutions. Chemical Communications. 2:218-220.

Interpretive Summary: The goal of our project is to develop new, environmentally benign methods to help convert a portion of the 800,000 lbs. of excess soybean oil produced in the U.S. to new, value-added uses, such as nutritional and cosmetic ingredients. One method we are developing involves the use of electron transfer proteins immobilized on electrodes that will convert vegetable oils to these value-added products when we supply voltage through the electrodes. In the course of developing the protein-electrode systems, we have discovered a fundamental property of the protein's, cytochrome c, behavior that is contrary to what has been reported in the scientific literature for the past ten years. The current manuscript details the basic research that was done to characterize and explain this unexpected behavior. These findings contribute to a fundamental understanding of the protein's behavior, which is essential in achieving our project's overall goal, and will also be useful to other scientists who are currently working with similar protein systems.

Technical Abstract: Transitory redox inactivation of cytochrome c (cyt-c) was observed after exposure of the protein to aqueous sodium chloride, sodium perchlorate, potassium chloride, or potassium perchlorate solutions of up to 1.0 M concentration, with and without up to 20 percent (v/v) ethanol or methanol. Redox activity of the protein was measured through cyclic voltammetry while adsorbed to a gold electrode modified with a self-assembled monolayer consisting of 11-mercapto-1-undecanol and 11-mercaptoundecanoic acid. Redox activity was recovered after incubation of the protein modified electrode in a 10 mM phosphate buffer solution, pH 7.0, containing no cyt-c. As procedures involving covalent immobilization of cyt-c to this and similar electrode systems are typically followed by a rinse with high-ionic strength solution to remove non-covalent protein, the temporary inactivation of the protein redox signal may mask unintended retention of electrostatically adsorbed protein.