A STD-NMR study of the interaction of the Anabaena ferredoxin-NAD reductase with the coenzyme

Ferredoxin-NAD reductase (FNR) catalyzes the electron transfer from ferredoxin to NAD via its flavin FAD cofactor. To get further insights in the architecture of the transient complexes produced during the hydride transfer event between the enzyme and the NAD coenzyme we have applied NMR spectroscopy using Saturation Transfer Difference (STD) techniques to analyze the interaction between FNRox and the oxidized state of its NAD coenzyme. We have found that STD NMR, together with the use of selected mutations on FNR and of the non-FNR reacting coenzyme analogue NA, are appropriate tools to provide further information about the the interaction epitope.