Adsorption of the natural protein surfactant Rsn-2 onto liquid interfaces

Brandani, G. B., Vance, S. J., Schor, M., Cooper, A., Kennedy, M. W., Smith, B. O., MacPhee, C. E. and Cheung, D. L. (2017) Adsorption of the natural protein surfactant Rsn-2 onto liquid interfaces. Physical Chemistry Chemical Physics, 19(12), pp. 8584-8594. (doi:10.1039/C6CP07261E) (PMID:28289744)

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Abstract

To stabilize foams, droplets and films at liquid interfaces a range of protein biosurfactants have evolved in nature. Compared to synthetic surfactants, these combine surface activity with biocompatibility and low solution aggregation. One recently studied example is Rsn-2, a component of the foam nest of the frog Engystomops pustulosus, which has been predicted to undergo a clamshell-like opening transition at the air–water interface. Using atomistic molecular dynamics simulations and surface tension measurements we study the adsorption of Rsn-2 onto air–water and cyclohexane–water interfaces. The protein adsorbs readily at both interfaces, with adsorption mediated by the hydrophobic N-terminus. At the cyclohexane–water interface the clamshell opens, due to the favourable interaction between hydrophobic residues and cyclohexane molecules and the penetration of cyclohexane molecules into the protein core. Simulations of deletion mutants showed that removal of the N-terminus inhibits interfacial adsorption, which is consistent with the surface tension measurements. Deletion of the hydrophilic C-terminus also affects adsorption, suggesting that this plays a role in orienting the protein at the interface. The characterisation of the interfacial behaviour gives insight into the factors that control the interfacial adsorption of proteins, which may inform new applications of this and similar proteins in areas including drug delivery and food technology and may also be used in the design of synthetic molecules showing similar changes in conformation at interfaces.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kennedy, Professor Malcolm and Smith, Dr Brian and Cooper, Professor Alan
Authors: Brandani, G. B., Vance, S. J., Schor, M., Cooper, A., Kennedy, M. W., Smith, B. O., MacPhee, C. E., and Cheung, D. L.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Science and Engineering > School of Chemistry
Journal Name:Physical Chemistry Chemical Physics
Publisher:Royal Society of Chemistry
ISSN:1463-9076
ISSN (Online):1463-9084
Published Online:27 February 2017
Copyright Holders:Copyright © 2017 Royal Society of Chemistry
First Published:First published in Physical Chemistry Chemical Physics 19(12): 8584-8594
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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