Long-range biological electron transfer (ET) reactions in enzymes are mediated by redox-active cofactors, or oxidizable protein side-chains, through precise pathways that not always clear. In the case of the Escherichia coli enzyme YhjA, quinol oxidation occurs at a N-terminal domain heme center (FeN) that then is coupled to the reduction of hydrogen peroxide at a low-redox potential, peroxidatic heme (FeL) that is more than 30 Å away. In between the two, a third His-/Met-ligated c-type heme (FeH) serves as an ET relay. Here we seek to understand how the two-electron chemistry of YhjA is mediated by one-electron redox cofactors, in order to develop a detailed view of the chemical mechanism of quinol oxidation being coupled to peroxide reduction. Here we present series of biochemical, spectroscopic and structural studies implicate Tyr432 as an additional relay for electron transfer from FeN to FeH, revising our model of YhjA catalysis.

Electron transfer pathways and kinetics of a triheme bacterial cytochrome c peroxidase, YhjA

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.