Scrambled Sequence Controls of Insulin Binding Polypeptide Used to Determine Surface Binding Behavior

We are interested in understanding selectivity in analyte binding behavior of short peptide sequences by controlling their attachment to surfaces. For example, insulin binding polypeptide (IBP, sequence CVEEAS) is a known recognition element that binds with insulin.¹ IBP, therefore, can be used for insulin detection, which means understanding its behavior is clinically relevant. Control experiments using a scrambled sequence of the amino acids that make up IBP can help in creating detection that is sensitive, selective, and repeatable. Our goal is to characterize the binding of this scrambled sequence (EACVES) as a control in order to confirm the selectivity of CVEEAS. In order to do this, electrode surfaces were chemically built with IBP using EDC/NHS chemistry. Electrochemical Impedance Spectroscopy (EIS) was used to mark changes on the surface and confirm binding of the IBP. By looking at the various outputs of EIS such as charge transfer resistance and phase shift, we can interpret these binding events. Understanding surface binding behavior allows electrochemical biosensing techniques to be properly executed and increases their potential for greater application in the medical field. By testing scrambled sequences of IBP we can understand its’ binding behavior and move towards creating a way to detect insulin on a surface.

Support was provided by a National Science Foundation EPSCoR award (#2119237).

1. Knutson, V. P. Insulin-binding Peptide Design and Characterization. J. Biol. Chem. 263, 14146–14151 (1988).