η − θ conformational space described by the monovalent-subset and divalent-subset. Results are divided into nonhelical North (panels
on the left) or South (panels on the right) sugar conformations. Density contours of 
(X = 1, 2, or 4; dark red, violet, and dark blue, respectively) highlight regions of the plots with a significant population
of nucleotides. Black dashed lines delimit the region occupied by canonical helical A-form (those structures are removed from
the analyses as described in the Materials and Methods section). (A) Densities and cluster analysis of the both types of cations together (monovalent in pink dots and divalent in turquoise)
over the clusters obtained for the complete-data set. (B) Clusters obtained by using only the monovalent-subset. (C) Idem than (B) using the divalent-subset.
