Bader Abdalhameed Almubarak
Dhahran Ahliyya School, Dammam, SAUDI ARABIA
The pathway of electron transfer reactions (ETRs) ensured by Geobacter sulfurreducens`s outer surface c-type cytochromes has been identified in previous studies. Geobacter sulfurreducens has been one of the most widely studied microorganisms capable of electricity generation for use in Microbial Fuel Cells. The chemistry of these ETRs needs to be thoroughly investigated in order to understand how this process can be efficiently reversed and utilized for energy storage. This study is aimed at expressing, purifying, and characterizing the OmcE protein, one of G. sulfurreducens` cytochrome c-type proteins, with the goal of understanding its role in the ETRs. The OmcE protein was cloned into the expression vector pET303-HisCT, has been expressed in a strain of E. coli (BL21), and attempts to purify it were made using His-tag purification and Ultrafiltration. Characterization was tested through oxydo-reduction. The heme-function was proven present in the purified fractions, and the OmcE protein did have a peak of UV-Visible light absorption at 407nm (when oxidized) and 417nm (when reduced), characteristic of heme groups. The OmcE protein in the purified fractions was identified and proven present (100%) via mass spectrometry yet likely to be associated with some other interesting proteins, including a Major Outer Membrane lipoprotein. The implications of this study will lead to integration with the comprehensive Bio-CCC (Biological carbon capture and conversion) project which is investigating possibilities to convert excess electric energy (e.g. from photovoltaics during the day) into hydrocarbons, which can serve to store and transport energy inexpensively and efficiently.