Peptide hairpin nucleation with the obligatory Type I' beta-turn Aib-DPro segment.

Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
Organic & Biomolecular Chemistry (Impact Factor: 3.49). 07/2010; 8(14):3133-5. DOI: 10.1039/c004577m
Source: PubMed

ABSTRACT The alpha-aminoisobutyric acid-D-proline (Aib-(D)Pro) dipeptide is an obligatory Type I' beta-turn forming segment that nucleates hairpin formation.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effect of incorporation of a centrally positioned Ac(6)c-Xxx segment where Xxx = (L)Val/(D)Val into a host oligopeptide composed of l-amino acid residues has been investigated. Studies of four designed octapeptides Boc-Leu-Phe-Val-Ac(6)c-Xxx-Leu-Phe-Val-OMe (Xxx = (D)Val 1, (L)Val 2) Boc-Leu-Val-Val-Ac(6)c-Xxx-Leu-Val-Val-OMe (Xxx = (D)Val 3, (L)Val 4) are reported. Diagnostic nuclear Overhouse effects characteristic of hairpin conformations are observed for Xxx = (D)Val peptides (1 and 3) while continuous helical conformation characterized by sequential N(i)H ↔ N(i+1)H NOEs are favored for Xxx = (L)Val peptides (2 and 4) in methanol solutions. Temperature co-efficient of NH chemical shifts are in agreement with distinctly different conformational preferences upon changing the configuration of the residue at position 5. Crystal structures of peptides 2 and 4 (Xxx = (L)Val) establish helical conformations in the solid state, in agreement with the structures deduced from NMR data. The results support the design principle that centrally positioned type I β-turns may be used to nucleate helices in short peptides, while type I'β-turns can facilitate folding into β-hairpins.
    Organic & Biomolecular Chemistry 02/2012; 10(14):2815-23. · 3.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The crystal structures of several designed peptide hairpins have been determined in order to establish features of molecular conformations and modes of aggregation in the crystals. Hairpin formation has been induced using a centrally positioned (D)Pro-Xxx segment (Xxx = (L)Pro, Aib, Ac6c, Ala; Aib = α-aminoisobutyric acid; Ac6c = 1-aminocyclohexane-1-carboxylic acid). Structures of the peptides Boc-Leu-Phe-Val-(D)Pro-(L)Pro-Leu-Phe-Val-OMe (), Boc-Leu-Tyr-Val-(D)Pro-(L)Pro-Leu-Phe-Val-OMe (, polymorphic forms labeled as and ), Boc-Leu-Val-Val-(D)Pro-(L)Pro-Leu-Val-Val-OMe (), Boc-Leu-Phe-Val-(D)Pro-Aib-Leu-Phe-Val-OMe (, polymorphic forms labeled as and ), Boc-Leu-Phe-Val-(D)Pro-Ac6c-Leu-Phe-Val-OMe () and Boc-Leu-Phe-Val-(D)Pro-Ala-Leu-Phe-Val-OMe () are described. All the octapeptides adopt type II' β-turn nucleated hairpins, stabilized by three or four cross-strand intramolecular hydrogen bonds. The angle of twist between the two antiparallel strands lies in the range of -9.8° to -26.7°. A detailed analysis of packing motifs in peptide hairpin crystals is presented, revealing three broad modes of association: parallel packing, antiparallel packing and orthogonal packing. An attempt to correlate aggregation modes in solution with observed packing motifs in crystals has been made by indexing of crystal faces in the case of three of the peptide hairpins. The observed modes of hairpin aggregation may be of relevance in modeling multiple modes of association, which may provide insights into the structure of insoluble polypeptide aggregates.
    Organic & Biomolecular Chemistry 05/2013; · 3.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: It is possible to atomize the liquid using surface acoustic wave (SAW) device. In this paper, we describe a novel atomization method based on SAW streaming. Stable generation and direction control of the mist are experimentally examined. We realize to continuously generate the mist by placing a filter paper, which retain a liquid on the SAW propagation surface. Also we demonstrate a mist direction control with an electrostatic field. Furthermore, practical atomization system is designed and performed.
    Ultrasonics, 2003 IEEE Symposium on; 11/2003


Available from