Designed peptides with homochiral and heterochiral diproline templates as conformational constraints

Chatterjee, Bhaswati ; Saha, Indranil ; Raghothama, Srinivasarao ; Aravinda, Subrayashastry ; Rai, Rajkishor ; Shamala, Narayanaswamy ; Balaram, Padmanabhan (2008) Designed peptides with homochiral and heterochiral diproline templates as conformational constraints Chemistry: A European Journal, 14 (20). pp. 6192-6204. ISSN 0947-6539

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Official URL: http://www3.interscience.wiley.com/journal/1191934...

Related URL: http://dx.doi.org/10.1002/chem.200702029

Abstract

Diproline segments have been advanced as templates for nucleation of folded structure in designed peptides. The conformational space available to homochiral and heterochiral diproline segments has been probed by crystallographic and NMR studies on model peptides containing L-Pro-L-Pro and D-Pro-L-Pro units. Four distinct classes of model peptides have been investigated: a) isolated D-Pro-L-Pro segments which form type II β-turn; b) D-Pro-L-Pro-L-Xxx sequences which form type II′-I (βII′-I′, consecutive β-turns) turns; c) D-Pro-L-Pro-D-Xxx sequences; d) L-Pro-L-Pro-L-Xxx sequences. A total of 17 peptide crystal structures containing diproline segments are reported. Peptides of the type Piv-D-Pro-L-Pro-L-Xxx-NHMe are conformationally homogeneous, adopting consecutive β-turn conformations. Peptides in the series Piv-D-Pro-L-Pro-D-Xxx-NHMe and Piv-L-Pro-L-Pro-L-Xxx-NHMe, display a heterogeneity of structures in crystals. A type VIa β-turn conformation is characterized in Piv-L-Pro-L-Pro-L-Phe-OMe (18), while an example of a 5→1 hydrogen bonded α-turn is observed in crystals of Piv-D-Pro-L-Pro-D-Ala-NHMe (11). An analysis of pyrrolidine conformations suggests a preferred proline puckering geometry is favored only in the case of heterochiral diproline segments. Solution NMR studies, reveal a strong conformational influence of the C-terminal Xxx residues on the structures of diproline segments. In L-Pro-L-Pro-L-Xxx sequences, the Xxx residues strongly determine the population of Pro-Pro cis conformers, with an overwhelming population of the trans form in L-Xxx = L-Ala (19).

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons, Inc.
Keywords:Beta Turns; Conformation Analysis; Peptide Folding; Peptides
ID Code:4973
Deposited On:18 Oct 2010 06:08
Last Modified:16 May 2016 15:33

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