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Guruprasad, K. and Pavan, M.N. and Rajkumar, S. and Swaminathan, S. (2000) Isolated and multiple b-turns with proline in the third position. Current Science, 79 (7). pp. 992-994. ISSN 0011-3891

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Abstract

We report the observation of a number of unexpected isolated β-turns with a proline in the third position. These β-turns are mainly, either type VIa1, type VIb or type IV although 3 examples of type I, 4 examples of type II′ and 5 examples of type VIa2 β-turns were also observed in a representative protein data set. Nearly a third of these turns are located in the loop regions and the rest are situated at ends of either helices or β-strands. The formation of double β-turns, where proline in the third position in the first β-turn corresponds to proline in second position in the second overlapping β-turn has earlier been suggested to stabilize the otherwise unfavourable proline in the third position. We observed a number of multiple β-turns, mainly of the type VIb or type IV, with proline in the third position that did not correspond to proline in second position in the overlapping β-turn. Although these β-turns may also be stabilized due to the formation of multiple turns, the isolated β-turns with proline residue in the third position are mainly surrounded by water molecules which are likely to stabilize these turns. The φ,ψ dihedral angle values for proline residue in isolated and multiple β-turns show distinct preferences in the Ramachandran plot.

Item Type: Article
Depositing User: Dr P Divakar
Date Deposited: 03 Nov 2015 05:00
Last Modified: 03 Nov 2015 06:02
URI: http://cdfd.sciencecentral.in/id/eprint/619

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