Conformation of 6,7-dimethyl-8-ribityllumazine bound to β-subunits of heavy riboflavin synthase: Transferred nuclear overhauser effect (TrNOE) studies employing ω1-13C-filtered NOESY including a novel technique for zero quantum suppression

Abstract

The β-subunits of heavy riboflavin synthase catalyze the formation of 6,7-dimethyl-8-ribityllumazine. The interaction of the13C-labelled enzyme product with isolated β-subunits was studied by transfer NOE measurements using ω1=13C-filtered NOESY and13C-1H-relayed NOESY. The advantages of these techniques are the removal of residual enzyme signals, the simplification of zero quantum suppression, and the improvement of water suppression which enabled the semiquantitative study of1H-1H distances of the ligand in the bound state. The preferred conformation of the ribityl side chain was calculated on the basis of the measured distances.