Refinement multiple-copy

Since NMR data may reflect the conformational averaging resulting from a substantial flexibility of DNA/RNA fragments, the parameters of the ensemble of structures obtained by MD refinement and experimental NMR restraints can display internal inconsistency. James and coworkers developed a method to determine the family of structural conform-ers and their populations based on NMR data [83]. This approach applies multiple-copy refinement with floating weights, which better reflects the conformational dynamics of nucleic acids. 

Pellegrini, M., Gronbech-Jensen, N., Kelly J. A., Pfluegl, G., and Yeates, T. O. (1997) Highly constrained multiple-copy refinement of protein crystal structures. Proteins 29, 426-432. 

For both of these renins multiple copies of the molecules have been independently defined in the x-ray analysis and shown to have very similar structures. These x-ray structures were refined to final agreement factors and correlation coefficients of 0.19 and 0.91 for human renin at 2.8 A resolution and... 

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