Classification of RNA backbone conformations into rotamers using (13)C′ chemical shifts: exploring how far we can go

The conformational space of the ribose-phosphate backbone is very complex as it is defined in terms of six torsional angles. To help delimit the RNA backbone conformational preferences, 46 rotamers have been defined in terms of these torsional angles. In the present work, we use the ribose experimental and theoretical (13)C′ chemical shifts data and machine learning methods to classify RNA backbone conformations into rotamers and families of rotamers. We show to what extent the experimental (13)C′ chemical shifts can be used to identify rotamers and discuss some problem with the theoretical computations of (13)C′ chemical shifts.