NMR-Based Configurational Assignments of Natural Products: Gibbs Sampling and Bayesian Inference Using Floating Chirality Distance Geometry Calculations

Floating chirality restrained distance geometry (fc-rDG) calculations are used to directly evolve structures from NMR data such as NOE-derived intramolecular distances or anisotropic residual dipolar couplings (RDCs). In contrast to evaluating pre-calculated structures against NMR restraints, multiple configurations (diastereomers) and conformations are generated automatically within the experimental limits. In this report, we show that the “unphysical” rDG pseudo energies defined from NMR violations bear statistical significance, which allows assigning probabilities to configurational assignments made that are fully compatible with the method of Bayesian inference. These “diastereomeric differentiabilities” then even become almost independent of the actual values of the force constants used to model the restraints originating from NOE or RDC data.

Incomplete Data Sets in the Model Free Analysis of Experimental Residual Dipolar Couplings in Small Organic Compounds

Residual dipolar couplings (RDCs) contain information on the relative arrangement and dynamics of internuclear spin vectors in chemical compounds. The recently introduced software TITANIA implements the MFA and extracts structure and dynamics parameters directly from experimental RDCs to facilitate <i>de novo</i> structure refinement for small organic compounds. Herein, we focus on the challenges faced with experimentally inaccessible data often encountered for small organic compounds leading to voids in the RDC matrix and the concomitant effects on the structure refinement. It is shown that RDC data sets obtained experimentally from currently available alignment media and measurement methods are of sufficient quality to allow relative configuration determination even when the relative configuration of the analyte is completely unknown.<br>

TITANIA: Model Free Interpretation of Residual Dipolar Couplings in the context of Organic Compounds

The direct use of RDCs as restraint to construct structures based on RDCs is proposed for organic compounds. It uses the vector and dynamics information available in multi alignment data sets directly for the joint determination of conformation and configuration of organic compounds. We show that employing these data even a flat or random start structure converges into the correctly configured structure when employing multiple alignment data sets in our iterative procedure. <br>

Incomplete Data Sets in the Model Free Analysis of Experimental Residual Dipolar Couplings in Small Organic Compounds

Residual dipolar couplings (RDCs) contain information on the relative arrangement and dynamics of internuclear spin vectors in chemical compounds. The recently introduced software TITANIA implements the MFA and extracts structure and dynamics parameters directly from experimental RDCs to facilitate <i>de novo</i> structure refinement for small organic compounds. Herein, we focus on the challenges faced with experimentally inaccessible data often encountered for small organic compounds leading to voids in the RDC matrix and the concomitant effects on the structure refinement. It is shown that RDC data sets obtained experimentally from currently available alignment media and measurement methods are of sufficient quality to allow relative configuration determination even when the relative configuration of the analyte is completely unknown.<br>

TITANIA: Model Free Interpretation of Residual Dipolar Couplings in the context of Organic Compounds

The direct use of RDCs as restraint to construct structures based on RDCs is proposed for organic compounds. It uses the vector and dynamics information available in multi alignment data sets directly for the joint determination of conformation and configuration of organic compounds. We show that employing these data even a flat or random start structure converges into the correctly configured structure when employing multiple alignment data sets in our iterative procedure. <br>

Model Free Analysis of Experimental Residual Dipolar Couplings in Small Organic Compounds

Residual dipolar couplings (RDCs) contain information on the relative arrangement and dynamics of internuclear spin vectors in chemical compounds. Classically, RDC data is analyzed by fitting to structure models, while...