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Effect of pH on the thermostability and redox properties of cytochrome c552 from Wolinella succinogenes
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Resumo(s)
Cytochrome c552 from Wolinella succinogenes is one of the few examples of a low reduction potential class I c-type cytochrome with a mixture of high/low spin state populations observed in its visible spectrum. Analysis of its structural model suggests that the heme is Met/His coordinated and highly solvent-exposed. This supports the hypothesis that it is the solvent accessibility of the propionate groups that controls the reduction potential of small c-type cytochromes. The visible spectra obtained at different pH values reveal the presence of a protonable group with a pKa of 7.3, which also influences the reduction potential of this small cytochrome c552 (Em 0' of 97 ± 5 mV, pH 7.0) and can be either an H2O/OH -group distantly coordinating the heme iron, or one of the propionate groups. The thermostability of cytochrome c552 has been studied by circular dichroism and differential scanning calorimetry, indicating a highly stable protein at pH 5-7 (90 ºC to 77 ºC).
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Acknowledgments
The authors acknowledge the Biolab for the acquisition of CD and DSC data, and Hugo Santos and the BIOSCOPE group for determining the molecular mass by LC-ESI-MS of the isolated Ws cytochrome
Palavras-chave
cytochrome c Wolinella succinogenes pH effect thermostability circular dichroism differential scanning calorimetry cyclic voltammetry Biochemistry Biophysics SDG 13 - Climate Action