Heme-thiolate proteins are important biological molecules with functions that range from gas sensing to circadian rhythm regulation. Heme-thiolate proteins are characterized by a charged sulfur atom attached to the iron atom in the center of the heme prosthetic group. Cysteine and histidine typically serve as the axial ligands to the iron atom in these proteins. Heme-thiolate proteins also vary in their coordination scheme and can be penta- or hexa-coordinated. Proteins that are hexa-coordinated can often switch the ligand in the sixth position in response to changes in the protein environment. This ligand switching appears to be a regulatory function. The ultimate goal of this research is to build models of heme-thiolate proteins using yeast iso-1-cytochrome <i>c</i> (cytc). So far, mutations have been made to cytc to change stability and possible ligation schemes. We are interested in measuring the stability of the variants using guanidine hydrochloride denaturation and optical spectra in order to create titration curves. By analyzing the titration curves relative protein stabilities can be determined. This allows us to compare our model proteins with other known heme-thiolate proteins and investigate what role protein stability plays in the ligand switch process.

Measuring the stability of iso-1-cytochrome<i> c</i> variants using heme spectra

249th National Meeting (2015)

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Measuring the stability of iso-1-cytochrome c variants using heme spectra