Formation of a transient [myoglobin (Mb), cytochrome b5 (cyt b5)] complex is required for the reductive repair of inactive ferri-Mb to its functional ferro-Mb state. The [Mb, cyt b5] complex exhibits a dynamic ensemble in which electron transfer (ET) reactive configurations are rare relative to nonreactive configurations and the complex is in rapid exchange between thermodynamically degenerate configurations. A Mb triple mutant was previously designed using an electrostatic interface redesign strategy in which the most thermodynamically favorable complex configuration is the most reactive configuration and overall binding is increased. This mutation not only speeds up the triplet ET quenching of the photoexcited M-porphyrin reconstituted Mb (M = Zn, Mg) by Fe3+b5, but also introduces much faster quenching of the excited singlet. Singlet quenching competes with singlet decay on the ps-ns timescale and the quenching rate constant is the sum of rate constants for fast ET and for resonance energy transfer.

Electron transfer and energy transfer in the [myoglobin, cytochrome <i>b<sub>5</sub></i>] complex

245th National Meeting (2013)

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Electron transfer and energy transfer in the [myoglobin, cytochrome b5] complex

Electron transfer and energy transfer in the [myoglobin, cytochrome b₅] complex