CROSREL: Full relaxation matrix analysis for NOESY and ROESY NMR spectroscopy
Leeflang, B., R.; Kroon-Batenburg, L., M.J.
Journal of Biomolecular NMR 2(5): 495-518
A method is proposed for quantitative analysis of ROESY peak intensities, to which corrections are applied for their offset dependence and for direct HOHAHA effects. Additionally the effects of anisotropic and internal motion can be assessed. This method has been implemented for full relaxation matrix analysis in the CROSREL program. Although CROSREL is applicable to NOESY data, its use for ROESY peak intensities has been evaluated here, because of its innovative character in this respect. The agreement between calculated and experimental intensities is expressed by a weighted residual R-w factor, similar to X-ray crystallography. The merits of the program have been tested on methyl(d3) beta-cellobioside, for which a ROESY buildup series has been acquired, and for which extensive MD simulations have been performed. It is concluded that correction for direct HOHAHA effects is obligatory for the analysis of ROESY data. Extension of the model for methyl beta-cellobioside with internal and anisotropic motion, as was derived from MD data, did not improve the results obtained for assumed isotropic tumbling of a rigid model. It has been shown that ROESY peak intensities can be analysed successfully by the CROSREL program.