A new approach for applying residual dipolar couplings as restraints in structure elucidation

Residual dipolar couplings are useful global structural restraints. The dip olar couplings define the orientation of a vector with respect to the align ment tensor. Although the size of the alignment tensor can be derived from the distribution of the experimental dipolar couplings, its orientation wit h respect to the coordinate system of the molecule is unknown at the beginn ing of structure determination. This causes convergence problems in the sim ulated annealing process. We therefore propose a protocol that translates d ipolar couplings into intervector projection angles, which are independent of the orientation of the alignment tensor with respect to the molecule. Th ese restraints can be used during the whole simulated annealing protocol.