Influence of Conformational Flexibility on Complexation-Induced Changes in Chemical Shift in a Neocarzinostatin Protein−Ligand Complex

In this paper is described an analysis of the effects of protein flexibility on the observed CIS values and the impact on the accuracy of 3D structures determined using a 1H NMR CIS approach. The effects of protein conformational mobility have been investigated by using a set of different protein structures as starting points for the calculation: the unbound X-ray crystal structure, the unbound NMR solution structure, and the bound NMR solution structure of the protein. The results indicated that loop movement does have a significant impact on the quality of the structure generated by the CIS structure determination methodology. The implementation of methods to treat loop flexibility within our protocol, however, did not improve the results for calculations based on the unbound protein frame.