Evidence of the Key Role of H<inf>3</inf>O<sup>+</sup> in Phospholipid Membrane Morphology

Cranfield, CG; Berry, T; Holt, SA; Hossain, KR; Le Brun, AP; Carne, S; Al Khamici, H; Coster, H; Valenzuela, SM; Cornell, B

Evidence of the Key Role of H<inf>3</inf>O<sup>+</sup> in Phospholipid Membrane Morphology

Cranfield, CG

Berry, T

Holt, SA

Hossain, KR

Le Brun, AP Carne, S Al Khamici, H Coster, H Valenzuela, SM

Cornell, B

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Publication Type:: Journal Article
Citation:: Langmuir, 2016, 32 (41), pp. 10725 - 10734
Issue Date:: 2016-10-18

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Field	Value	Language
dc.contributor.author	Cranfield, CG https://orcid.org/0000-0003-3608-5440	en_US
dc.contributor.author	Berry, T https://orcid.org/0000-0002-2882-0313	en_US
dc.contributor.author	Holt, SA https://orcid.org/0000-0003-3189-8047	en_US
dc.contributor.author	Hossain, KR https://orcid.org/0000-0003-4506-1491	en_US
dc.contributor.author	Le Brun, AP	en_US
dc.contributor.author	Carne, S	en_US
dc.contributor.author	Al Khamici, H	en_US
dc.contributor.author	Coster, H	en_US
dc.contributor.author	Valenzuela, SM https://orcid.org/0000-0001-5934-6047	en_US
dc.contributor.author	Cornell, B https://orcid.org/0000-0003-4166-3241	en_US
dc.date.available	2020-05-25T19:09:16Z
dc.date.issued	2016-10-18	en_US
dc.identifier.citation	Langmuir, 2016, 32 (41), pp. 10725 - 10734	en_US
dc.identifier.issn	0743-7463	en_US
dc.identifier.uri	http://hdl.handle.net/10453/54908
dc.description.abstract	© 2016 American Chemical Society. This study explains the importance of the phosphate moiety and H3O+ in controlling the ionic flux through phospholipid membranes. We show that despite an increase in the H3O+ concentration when the pH is decreased, the level of ionic conduction through phospholipid bilayers is reduced. By modifying the lipid structure, we show the dominant determinant of membrane conduction is the hydrogen bonding between the phosphate oxygens on adjacent phospholipids. The modulation of conduction with pH is proposed to arise from the varying H3O+ concentrations altering the molecular area per lipid and modifying the geometry of conductive defects already present in the membrane. Given the geometrical constraints that control the lipid phase structure of membranes, these area changes predict that organisms evolving in environments with different pHs will select for different phospholipid chain lengths, as is found for organisms near highly acidic volcanic vents (short chains) or in highly alkaline salt lakes (long chains). The stabilizing effect of the hydration shells around phosphate groups also accounts for the prevalence of phospholipids across biology. Measurement of ion permeation through lipid bilayers was made tractable using sparsely tethered bilayer lipid membranes with swept frequency electrical impedance spectroscopy and ramped dc amperometry. Additional evidence of the effect of a change in pH on lipid packing density is obtained from neutron reflectometry data of tethered membranes containing perdeuterated lipids.	en_US
dc.relation	http://purl.org/au-research/grants/arc/DP160101664
dc.relation	http://purl.org/au-research/grants/arc/LP120200078
dc.relation.ispartof	Langmuir	en_US
dc.relation.isbasedon	10.1021/acs.langmuir.6b01988	en_US
dc.subject.classification	Chemical Physics	en_US
dc.title	Evidence of the Key Role of H<inf>3</inf>O<sup>+</sup> in Phospholipid Membrane Morphology	en_US
dc.type	Journal Article
utslib.citation.volume	41	en_US
utslib.citation.volume	32	en_US
utslib.for	0601 Biochemistry and Cell Biology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CHT - Health Technologies
pubs.organisational-group	/University of Technology Sydney/Strength - IBMD - Initiative for Biomedical Devices
pubs.organisational-group	/University of Technology Sydney/Students
utslib.copyright.status	open_access
pubs.issue	41	en_US
pubs.publication-status	Published	en_US
pubs.volume	32	en_US

Abstract:

© 2016 American Chemical Society. This study explains the importance of the phosphate moiety and H3O+ in controlling the ionic flux through phospholipid membranes. We show that despite an increase in the H3O+ concentration when the pH is decreased, the level of ionic conduction through phospholipid bilayers is reduced. By modifying the lipid structure, we show the dominant determinant of membrane conduction is the hydrogen bonding between the phosphate oxygens on adjacent phospholipids. The modulation of conduction with pH is proposed to arise from the varying H3O+ concentrations altering the molecular area per lipid and modifying the geometry of conductive defects already present in the membrane. Given the geometrical constraints that control the lipid phase structure of membranes, these area changes predict that organisms evolving in environments with different pHs will select for different phospholipid chain lengths, as is found for organisms near highly acidic volcanic vents (short chains) or in highly alkaline salt lakes (long chains). The stabilizing effect of the hydration shells around phosphate groups also accounts for the prevalence of phospholipids across biology. Measurement of ion permeation through lipid bilayers was made tractable using sparsely tethered bilayer lipid membranes with swept frequency electrical impedance spectroscopy and ramped dc amperometry. Additional evidence of the effect of a change in pH on lipid packing density is obtained from neutron reflectometry data of tethered membranes containing perdeuterated lipids.

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http://hdl.handle.net/10453/54908