Ultrafast electron transfer in riboflavin binding protein in macromolecular crowding of nano-sized micelle

► Electron transfer dynamics of Rf in RBP is studied under SDS as crowding agent. ► RBP losses Rf binding capacity above 1.5 mM of SDS. ► Secondary structure of the protein is strengthened in presence of SDS. ► Tertiary structure of RBP collapses from native to a molten globular like state. ► Electron transfer from RBP to Rf decreases with the gradual addition of SDS.