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Project Progress

The major emphasis of the research in the ABRC is relating the structure and reactivity of iron-sulfur minerals and iron-sulfur enzymes to better understand the origin of biological processes. Specifically we are using iron-sulfur motifs as a model system to understand the transition between the abiotic early Earth and biology. We have been able to provide growing support for our overarching hypothesis that there is a distinct connection between iron-sulfur minerals and iron-sulfur enzymes worthy of this line of inquiry in work on the complex iron sulfur containing nitrogenases (nitrogen fixation) and hydrogenases (hydrogen metabolism). The enzymes responsible for reversible carbon dioxide oxidation (carbon monoxide dehydrogenases) are also complex iron-sulfur enzymes. In this project we are testing the hypothesis that the path from minerals to enzymes occur through the organic nesting of clusters and that the evolutionary ancestors of modern iron sulfur enzymes were simply peptides or polypeptides capable of binding metal clusters. In this work we have used a model enzyme which we have structurally characterized and found to have an open cavity with metal binding ligands and the capacity to bind metal clusters. When we incubate this protein with the various concentrations of nickel, iron, and sulfur we are able to generate different metal clusters some of which have detectable levels of carbon monoxide oxidation catalytic activity. We are in the process now of designing minimal cluster forming peptide motifs to indentify the minimum structural determinants of catalysis.