CONFORMATION OF 6,7-DIMETHYL-8-RIBITYLLUMAZINE BOUND TO BETA-SUBUNITS OF HEAVY RIBOFLAVIN SYNTHASE - TRANSFERRED NUCLEAR OVERHAUSER EFFECT (TRNOE) STUDIES EMPLOYING OMEGA-1-C-13-FILTERED NOESY INCLUDING A NOVEL TECHNIQUE FOR ZERO QUANTUM SUPPRESSION

The beta-subunits of heavy riboflavin synthase catalyze the formation of 6,7-dimethyl-8-ribityllumazine. The interaction of the C-13-labelled enzyme product with isolated beta-subunits was studied by transfer NOE measurements using omega-1-C-13-filtered NOESY and C-13-H-1-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 of H-1-H-1 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.