From folding to function: design of a new switchable biosurfactant protein

Zhao, Chun-Xia, Dwyer, Mirjana, Yu, Lei and Middelberg, Anton P. J. (2017) From folding to function: design of a new switchable biosurfactant protein. ChemPhysChem, 18 5: 488-492. doi:10.1002/cphc.201601277

Author Zhao, Chun-Xia
Dwyer, Mirjana
Yu, Lei
Middelberg, Anton P. J.
Title From folding to function: design of a new switchable biosurfactant protein
Journal name ChemPhysChem   Check publisher's open access policy
ISSN 1439-7641
Publication date 2017-01-16
Sub-type Article (original research)
DOI 10.1002/cphc.201601277
Open Access Status Not yet assessed
Volume 18
Issue 5
Start page 488
End page 492
Total pages 6
Place of publication Weinheim, Germany
Publisher Wiley - V C H Verlag GmbH & Co. KGaA
Language eng
Subject 3107 Atomic and Molecular Physics, and Optics
1606 Physical and Theoretical Chemistry
Abstract A new anionic biosurfactant protein (SP16) capable of tuning foaming behaviour by pH or salt has been designed. This biosurfactant exhibits unique foaming behaviour with high sensitivity to pH. A good level of foaming was observed at pH2 but not at pH3. A further increase by one pH unit to pH4 restored good foaming. At pH5-8, SP16 again showed low foaming propensity, whereas the presence of salt (NaCl) was able to restore foaming again. Interfacial tension and circular dichroism investigations revealed the foaming control mechanism. The high negative charge (-16.6) at pH6 and above restricted the ability of SP16 to fold into an α-helical conformation and also restricted surface activity. For pH5 (-13.6), even though SP16 folds in bulk to give α-helical structure, the high charge inhibited adsorption at the air-water interface, resulting in a significant lag time of about 150-200sec to achieve a decrease in interfacial tension. In contrast to its low foaming behaviour at pH5-8, the presence of salt (NaCl) was found to effectively screen negative charge, thus leading to its folding and a decrease of interfacial tension. This new design offers a new strategy to control foaming behaviour, and elaborates a clear link between charge, structure and interfacial activity for biosurfactants.
Keyword Biosurfactants
Protein folding
Surface activity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
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Australian Institute for Bioengineering and Nanotechnology Publications
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