Simple multidimensional NMR experiments to obtain different types of one-bond dipolar couplings simultaneously

In order to measure residual dipolar couplings, the molecule under study ha s to be partially oriented in the presence of the magnetic field. It has be en observed that some protein samples are not stable under the conditions i mposed by the orienting media. If different types of dipolar couplings are measured sequentially, their values will not agree with a unique alignment tensor that is changing slowly over time. This could bias the structure cal culation. It would be more appropriate to obtain different types of dipolar couplings simultaneously, such that all the data correspond to one effecti ve alignment tensor. We describe here a general NMR strategy designed to do so, that can be adapted to various existing pulse sequences.