An Electrochemical Model for Interfacial Protein Interactions.
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The goal of this research is to study the role tryptophan 48 plays in the oxidation-reduction chemistry of azurin: a mononuclear blue copper protein found in the gram-negative bacterium Pseudomonas aeruginosa. Trp48, which is located close to the copper center, has been selectively conserved throughout the cupredioxin family, leading us to believe that it plays a vital role in fine-tuning the redox potential of the metalloprotein. Using site-directed mutagenesis, the 48<sup>th</sup> position can be altered from tryptophan to alanine, theoretically changing the redox potential of azurin. Through examining the shift in the mutant azurin?s redox potential we hope to gain a greater understanding of tryptophan 48?s importance in electron transport. The current focus is on unfolding the Trp48Ala mutant and refolding it in the presence of exogenous indole. Structurally, indole is identical to the bicyclic ring the tryptophan loses when mutated to alanine. We expect that under certain conditions the mutant, in an effort to increase its stability, will incorporate the indole upon refolding. With the incorporated indole, it is predicted that wild-type properties will be restored. We will then compare the refolded mutant protein?s redox potential to that of wild-type azurin, as well as the mutant?s redox potential prior to indole incorporation. Continued research will focus on this as well as introducing synthetic amino acids through the incorporation of substituted indoles.