Calmodulin is a calcium binding protein seen in all eukaryotic cells. In this experiment, CaM has been labeled with fluorescence dyes bound to specific mutation sites to investigate the secondary structure of the protein in high and low calcium buffers. Previous experiments in our lab suggested that fluorescence dyes may interact strongly with the protein. The methods involved a novelty use for circular dichroism by probing the dye’s visible absorption region (500-650 nm) to investigate interactions of the dyes with the protein. The dyes Texas Red and Alexa Fluor 594 had low optical activity in the absence of the protein. For labeled proteins, however, we observed significant circular dichroism at the T34C mutation site when bound to either AF594 or Texas Red, as compared to the T110C mutation site which presented with weak to moderately observed circular dichroism for AF594 and Texas Red respectively.

Dye-protein investigation with circularly polarized light

251st National Meeting (2016)

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