@article{open1864,
          volume = {6},
          author = {Jesmita Dhar and Raghuvansh Kishore and Pinak Chakrabarti},
            note = {Open Access},
           title = {A novel secondary structure based on fused five-membered rings motif.},
       publisher = {NPG},
         journal = {Scientific reports},
           pages = {31483},
            year = {2016},
        keywords = {Protein Analysis; Structure biology},
             url = {http://crdd.osdd.net/open/1864/},
        abstract = {An analysis of protein structures indicates the existence of a novel, fused five-membered rings motif, comprising of two residues (i and i + 1), stabilized by interresidue Ni+1-H???Ni and intraresidue Ni+1-H???O=Ci+1 hydrogen bonds. Fused-rings geometry is the common thread running through many commonly occurring motifs, such as {\ensuremath{\beta}}-turn, {\ensuremath{\beta}}-bulge, Asx-turn, Ser/Thr-turn, Schellman motif, and points to its structural robustness. A location close to the beginning of a {\ensuremath{\beta}}-strand is rather common for the motif. Devoid of side chain, Gly seems to be a key player in this motif, occurring at i, for which the backbone torsion angles cluster at {\texttt{\char126}}(-90?, -10?) and (70?, 20?). The fused-rings structures, distant from each other in sequence, can hydrogen bond with each other, and the two segments aligned to each other in a parallel fashion, give rise to a novel secondary structure, topi, which is quite common in proteins, distinct from two major secondary structures, {\ensuremath{\alpha}}-helix and {\ensuremath{\beta}}-sheet. Majority of the peptide segments making topi are identified as aggregation-prone and the residues tend to be conserved among homologous proteins.}
}