Statistical evaluation of simulated NMR data of flexible molecules

Abstract

A new probability score—named χ-probability—is introduced for evaluating the fit of mixed NMR datasets to calculate molecular model ensembles, in order to answer challenging structural questions such as the determination of stereochemical configurations.

Extending molecular dynamics with dipolar NMR tensors as constraints to chiral phosphorus compounds

“…16 In the present investigation, a 40 ns MDOC simulation was performed for both stereoisomers with the data sets 1A and 1B (for the parameters of the simulation see the ESI †). For both datasets, 1A and 1B, the quality factors 28 n/w 2 (details in the section ''Computational methods'') were low, reaching 0.1 and 0.2, respectively, due to the relatively small 13 C-31 P couplings and narrow error ranges. Because these quality factor values prevented us from assigning the relative configuration, we calculated the w-probability 28 (Table S10, ESI †) and assigned dataset 1A as 1-SR by 90%, in line with X-ray data.…”

“…The w-probability has been recently developed to incorporate several types of data (RDCs and 3 J couplings in this study) into a consistent tool. 28 The formalism of the w-probability was developed on the same basis as the well established Bayesian measure DP4 developed by Smith and Goodman 29 as stereochemical score using chemical shifts. The w-probability differs from DP4 in the following points: (i) instead of chemical shift differences, absolute w-values are used, and (ii) the normal distribution is used for defining the probability that a calculated value differs from the experiment under consideration of the individual error.…”