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Volume 12   Issue 2   Year 2017
Analysis of the Torsion Angles between Helical Axes in Pairs of Helices in Protein Molecules

Tikhonov D.A., Kulikova L.I., Efimov A.V.

Institute of Mathematical Problems of Biology RAS – the Branch of Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Pushchino, Russia
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Russia
Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Russia

Abstract. In this study, an analysis of distribution of the torsion angles Ω between helical axes in pairs of connected helices found in known proteins has been performed. The database for helical pairs was compiled using the Protein Data Bank taking into account the definite rules suggested earlier. The database was analyzed in order to elaborate its classification and find out novel structural features in helix packing. The database was subdivided into three subsets according to criterion of crossing helix projections on the parallel planes passing through the axes of the helices. It was shown that helical pairs not having crossing projections are distributed along whole range of angles Ω, although there are two maxima at Ω = 0° and Ω = 180°. Most of helical pairs of this subset are pairs formed by α-helices and 310- helices. It is shown that the distribution of all the helical pairs having the crossing helix projections has a maximum at 20° < Ω < 25°. In this subset, most helical pairs are formed by α-helices. The distribution of only α-helical pairs having crossing axes projections has three maxima, at –50° < Ω < –25°, 20° < Ω < 25°, and 70° < Ω < 110°.
Key wordsstructural motifs of proteins, pairs of helices, the point model,  the torsion angle between  axes of the helices.
Table of Contents Original Article
Math. Biol. Bioinf.
doi: 10.17537/2017.12.398
published in Russian

Abstract (rus.)
Abstract (eng.)
Full text (rus., pdf)
References Translation into English
Math. Biol. Bioinf.
doi: 10.17537/2018.13.t17

Full text (eng., pdf)


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