SOLUTION-STATE STRUCTURE OF NATIVE COENZYME F430 BY NMR METHODS

Solution-state structure of native F430 was determined by using NMR me thods and NMR-based distance geometry (DG) computations. Structures we re generated with loose NOE-derived interproton distance restraints (2 .0-2.5 Angstrom, 2.0-3.5 Angstrom and 2.0-4.5 Angstrom for strong, med ium, and weak NOE cross-peak intensities, respectively). 2D NOESY back -calculations of structures were subsequently carried out for establis hing the consistence between experimental data and DG-model structures . The back-calculated 2D NOESY spectra of resulting DG structures were well consistent with experimental 2D NOESY spectra. Superposition of 20 independent structures with macrocyclic ring atoms and all atoms of F430 afforded pairwise root mean square deviations (RMSD) of 0.025-0. 125 Angstrom and 0.64-1.3 Angstrom respectively. The macrocyclic rings of structures are well converged to a unique conformation with saddle -shaped deformation whereas most of side chains are not converged. The average dihedral angle (N1-N2-N3-N4, 27.78+/-1.50 degrees) of 20 DG-s tructures exhibits that the macrocyclic ring conformation is puckered as much as 12,13-diepimeric F430 (28.75+/-4.07 degrees).