Zusammenfassung
The coordination of flavins to Lewis-acidic zinc(II)cyclen complexes, as a mimic for a metalloprotein binding site, changes their redox properties significantly. The coordination facilitates the electrochemical reduction of the flavin and stabilizes the flavinhydroquinone redox stage, so that a 600 mV more positive potential is necessary for reoxidation. Binding of flavin to the receptor molecule ...
Zusammenfassung
The coordination of flavins to Lewis-acidic zinc(II)cyclen complexes, as a mimic for a metalloprotein binding site, changes their redox properties significantly. The coordination facilitates the electrochemical reduction of the flavin and stabilizes the flavinhydroquinone redox stage, so that a 600 mV more positive potential is necessary for reoxidation. Binding of flavin to the receptor molecule is not restricted to nonpolar solvents and works in methanol. Here, interception of the ECE mechanism of reduction is possible leading to a stabilization of the flavosemiquinone radical anion redox stage, which was proved by its characteristic UV absorption in spectroelectrochemistry. Although it has not yet been observed in flavoproteins, this study shows that flavin binding by coordination to a metal binding site is suitable for cofactor binding and modulation of its redox properties as well as other intermolecular interactions.
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