The K79G Mutation Reshapes the Heme Crevice and Alters Redox Properties of Cytochrome c

Biochemistry
Yunling DengEkaterina V Pletneva

Abstract

The two roles of cytochrome c (cyt c), in oxidative phosphorylation and apoptosis, critically depend on redox properties of its heme iron center. The K79G mutant has served as a parent protein for a series of mutants of yeast iso-1 cyt c. The mutation preserves the Met80 coordination to the heme iron, as found in WT* (K72A/C102S), and many spectroscopic properties of K79G and WT* are indistinguishable. The K79G mutation does not alter the global stability, fold, rate of Met80 dissociation, or thermodynamics of the alkaline transition (p Ka) of the protein. However, the reduction potential of the heme iron decreases; further, the p KH of the trigger group and the rate of the Met-to-Lys ligand exchange associated with the alkaline transition decrease, suggesting changes in the environment of the heme. The rates of electron self-exchange and bimolecular electron transfer (ET) with positively charged inorganic complexes increase, as does the intrinsic peroxidase activity. Analysis of the reaction rates suggests that there is increased accessibility of the heme edge in K79G and supports the importance of the Lys79 site for bimolecular ET reactions of cyt c, including those with some of its native redox partners. Structural modeling ...Continue Reading

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Citations

Jun 11, 2019·Journal of the American Chemical Society·Fangfang Zhong, Ekaterina V Pletneva
Oct 8, 2019·Inorganic Chemistry·Yunling DengEkaterina V Pletneva
Oct 27, 2021·Inorganic Chemistry·Fangfang ZhongEkaterina V Pletneva

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