Site-Directed Mutagenesis of a Blue Copper Protein

Abstract

Stellacyanin is a blue copper-binding protein of unknown biological function. We propose to combine the copper binding ability of Stellacyanin with the elcetron carrying capacity of DNA to create a potential difference from one end of the DNA to the other.Stellacyanin is ideal for this purpose as its copper-binding domain lies at one end of its primary sequence. We intend to modify the binding domain in an attempt to alter the bond length between protein and copper. In addition we will add a DNA binding domain at the other terminus of the protein. Ideally the DNA will carry charge between two versions of the protein, each with a difference copper bond length. Such a system could function as a bridge between an electron source and a site where reductive chemistry takes place. Our initial experiment is the growth of Stellacyanin with an unmodified copper binding domain and the addition of a DNA binding domain. It is our intent to tether the protein to an electrode with a DNA wire in order to measure its reductive potential.