Cytochrome c in sodium dodecyl sulfate reverse micelle nanocage: From a classic electron carrier protein to an artificial peroxidase enzyme

Cytochrome c (Cyt c) is a hemoprotein involved in shuttling electrons in the mitochondrial electron transport chain. Under oxidative stress conditions, the interaction of Cyt c with anionic phospholipids results in significant enhancement of its peroxidase activity that is essential during apoptosis. Reverse micelles are convenient membrane mimetic nanostructures and were used here to simulate Cyt c peroxidase activity. Cyt c peroxidase activity was markedly enhanced in sodium dodecyl sulfate (SDS) reverse micelles. This was dependent on buffer concentration of water pool and mass percentage of buffer in reverse micelles. Fluorescence intensity based on tryptophan residue, electronic absorption curves, and circular dichroism measurements indicated partial unfolding and cleavage of axial methionin 80-Fe bond of Cyt c in reverse micellar medium resulting in the formation of a peroxidase-like artificial enzyme.