Physical quantity of residue electrostatic energy in flavin mononucleotide binding protein dimer

•The Electrostatic (ES) energy of each residue was first time quantitatively evaluated in flavin mononucleotide binding protein (FBP).•Among all residues, both Arg63 and Glu13 mainly contribute to Sub A–Sub B binding.•The FMN molecule greatly stabilizes the protein structure within a subunit.•The present work reveals that the ES energy not only plays an important role on ET phenomena but also in the protein stabilization in general.