Modulation of Flavin Recognition and Redox Properties through Donor Atom−π Interactions

Computational and experimental model studies establish the importance of donor atom−π bonding on the recognition and function of flavins. This noncovalent interaction arises from electrostatic attraction between electron-rich (donor) atoms and electron-deficient aromatic systems. The electrostatic origin of this bonding was verified through comparison of binding of model receptors to flavin in both oxidized (Flox) and radical anion (Flrad-) forms: Interaction was strongest with the electron-poor Flox and was greatly attenuated with the comparatively electron-rich Flrad-. Other factors determining the magnitudes of these donor−π interaction are the size and polarizability of the donor atom.