One- and Two- Electron Reductions in MiniSOG and their Implication in Catalysis.

Abstract

In the last years, the unconventional bioorthogonal catalytic activation of anticancer metal complexes by flavin and flavoproteins photocatalysis has been described. The reactivity is based on a two-electron redox reaction of the photoactivated flavin. Furthermore, when it comes to flavoproteins, we recently reported that site mutagenesis can modulate and improve this catalytic activity in the mini Singlet Oxygen Generator protein (SOG). In this paper, we analyze the reductive half-reaction in the different miniSOG environments by means of density functional theory. We report that the redox properties of the flavin and the resulting reactivity of miniSOG is modulated by specific mutations, in line with the experimental results in the literature. This modulation can be attributed to fundamental physicochemical properties of the system, specifically (i) the competition of single and double reduction of the flavin and (ii) the probability of electron transfer from the protein to the flavin. These factors are ultimately linked to the stability of the electronaccepting orbitals of the flavin in the different coordination modes.