MO study of flavin reduction

MINDO /3 calculations have been performed on semiquinone and fully reduced lumiflavins and on hydroperoxy adducts of lumiflavin. Frontier orbital indices were calculated. Reduction of the flavin was studied in bent and planar flavin rings. The results suggest that the planar reduced flavin has a smaller ionization potential than the bent reduced flavin. This could account for the low redox potential of protein-bound reduced flavins.