Proteins in psychrophilic organisms must delicately balance stability and flexibility for success at low temperatures (0 ± 10 °C). We suggest that the requirements of electron-transfer proteins such as cytochrome c may be different from those of enzymes. Using site-directed mutagenesis, UV-visible absorption and circular dichroism spectroscopies, electrochemistry, and computational chemistry, we have investigated the thermodynamics of cytochrome c552 from the psychrophilic, hydrocarbonoclastic bacterium Colwellia psychrerythraea 34H. We find a specific Phe–Arg cation-π interaction is essential for tuning the reduction potential and providing stability to the protein, and we discuss the broader implications of this result.

Essential cation-π interaction in a psychrophilic electron transfer protein

251st National Meeting (2016)

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