
Trends in natural sequences. Distributions of folding free energy change, ensemble folding free energy change, ensemble defect, and structure probability for 7 bp helices. Cumulative distribution plots are provided in red for unique sequences observed in the database of RNA structures and in blue for all possible helices. Panel A is Gibbs free energy change, panel B is ensemble Gibbs free energy change, panel C is ensemble defect, and panel D is the probability of helix formation.










