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

Area of Science:

• Biochemistry
• Computational Chemistry
• Photocatalysis

Background:

• Bioorthogonal photocatalysis using flavins and flavoproteins offers a novel approach for activating anticancer metal complexes.
• This activation relies on a two-electron redox reaction involving photoactivated flavin.
• Site-directed mutagenesis in flavoproteins, such as the mini Singlet Oxygen Generator protein (miniSOG), can enhance catalytic activity.

Purpose of the Study:

• To computationally analyze the reductive half-reaction of flavin within different miniSOG environments.
• To understand how protein mutations modulate the redox properties and catalytic activity of flavoproteins.
• To elucidate the underlying physicochemical factors influencing flavin-based photocatalysis.

Main Methods:

• Density functional theory (DFT) calculations were employed to study the reductive half-reaction.
• Analysis focused on miniSOG environments with varying protein mutations.
• Investigated the competition between single and double flavin reduction and electron transfer probabilities.

Main Results:

• Specific mutations in miniSOG were found to significantly modulate the redox properties of flavin.
• These modulations directly impact the catalytic reactivity of miniSOG, aligning with experimental observations.
• The study identified the stability of flavin's electron-accepting orbitals as a key factor influenced by protein coordination.

Conclusions:

• Protein mutations play a crucial role in tuning flavin-based photocatalysis for bioorthogonal applications.
• Computational analysis provides insights into the mechanisms of redox modulation in flavoproteins.
• Understanding these principles can guide the rational design of improved flavoprotein catalysts for cancer therapy.