Sticky water surfaces: Helix–coil transitions suppressed in a cell-penetrating peptide at the air-water interface

Schach, Denise, Globisch, Christoph, Roeters, Steven J., Woutersen, Sander, Fuchs, Adrian, Weiss, Clemens K., Backus, Ellen H. G., Landfester, Katharina, Bonn, Mischa, Peter, Christine and Weidner, Tobias (2014) Sticky water surfaces: Helix–coil transitions suppressed in a cell-penetrating peptide at the air-water interface. The Journal of Chemical Physics, 141 22: 22D517.1-22D517.9. doi:10.1063/1.4898711

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Author Schach, Denise
Globisch, Christoph
Roeters, Steven J.
Woutersen, Sander
Fuchs, Adrian
Weiss, Clemens K.
Backus, Ellen H. G.
Landfester, Katharina
Bonn, Mischa
Peter, Christine
Weidner, Tobias
Title Sticky water surfaces: Helix–coil transitions suppressed in a cell-penetrating peptide at the air-water interface
Journal name The Journal of Chemical Physics   Check publisher's open access policy
ISSN 0021-9606
1520-9032
Publication date 2014-10-29
Year available 2014
Sub-type Article (original research)
DOI 10.1063/1.4898711
Open Access Status File (Publisher version)
Volume 141
Issue 22
Start page 22D517.1
End page 22D517.9
Total pages 10
Place of publication College Park, MD United States
Publisher American Institute of Physics
Collection year 2015
Language eng
Formatted abstract
GALA is a 30 amino acid synthetic peptide consisting of a Glu-Ala-Leu-Ala repeat and is known to undergo a reversible structural transition from a disordered to an α-helical structure when changing the pH from basic to acidic values. In its helical state GALA can insert into and disintegrate lipid membranes. This effect has generated much interest in GALA as a candidate for pH triggered, targeted drug delivery. GALA also serves as a well-defined model system to understand cell penetration mechanisms and protein folding triggered by external stimuli. Structural transitions of GALA in solution have been studied extensively. However, cell penetration is an interfacial effect and potential biomedical applications of GALA would involve a variety of surfaces, e.g., nanoparticles, lipid membranes, tubing, and liquid-gas interfaces. Despite the apparent importance of interfaces in the functioning of GALA, the effect of surfaces on the reversible folding of GALA has not yet been studied. Here, we use sum frequency generation vibrational spectroscopy (SFG) to probe the structural response of GALA at the air-water interface and IR spectroscopy to follow GALA folding in bulk solution. We combine the SFG data with molecular dynamics simulations to obtain a molecular-level picture of the interaction of GALA with the air-water interface. Surprisingly, while the fully reversible structural transition was observed in solution, at the water-air interface, a large fraction of the GALA population remained helical at high pH. This “stickiness” of the air-water interface can be explained by the stabilizing interactions of hydrophobic leucine and alanine side chains with the water surface.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
Australian Institute for Bioengineering and Nanotechnology Publications
 
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Created: Thu, 30 Oct 2014, 18:25:56 EST by Adrian Fuchs on behalf of Aust Institute for Bioengineering & Nanotechnology