Before revision: There is little objective insight about various statistical aspects regarding the nature of occurrences of 3-10 and Pi-helices. Comprehensive set of reasons behind the existence of 3-10 and Pi-helices can only be obtained if the occurrence profile of these on the primary structure is unambiguously described from the perspectives of sequence, structure and evolution. Although studies about the compositional and energetic profile of 3-10 and Pi-helices aren't uncommon, merely that doesn't tell us why these (rather unstable) structures are found in the proteins at the first place. Considering all the non-redundant protein structures across all the major structural classes, the present study attempts to find the probabilistic distributions that describe several facets of the occurrence of these rare secondary structures in proteins.
After revision: Considering all available non-redundant protein structures across all the major structural classes, the present study attempts to find the probabilistic distributions that describe several facets of the occurrence of these rare secondary structures in proteins.