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Brown KL, Conboy JC. Phosphatidylglycerol Flip-Flop Suppression due to Headgroup Charge Repulsion. J Phys Chem B. 2015;119(32):10252-60doi: 10.1021/acs.jpcb.5b05523.
Brown, K. L., & Conboy, J. C. (2015). Phosphatidylglycerol Flip-Flop Suppression due to Headgroup Charge Repulsion. The journal of physical chemistry. B, 119(32), 10252-60. https://doi.org/10.1021/acs.jpcb.5b05523
Brown, Krystal L, and Conboy, John C. "Phosphatidylglycerol Flip-Flop Suppression due to Headgroup Charge Repulsion." The journal of physical chemistry. B vol. 119,32 (2015): 10252-60. doi: https://doi.org/10.1021/acs.jpcb.5b05523
Brown KL, Conboy JC. Phosphatidylglycerol Flip-Flop Suppression due to Headgroup Charge Repulsion. J Phys Chem B. 2015 Aug 13;119(32):10252-60. doi: 10.1021/acs.jpcb.5b05523. Epub 2015 Aug 04. PMID: 26202012.
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J Phys Chem B. 2015 Aug 13;119(32):10252-60. doi: 10.1021/acs.jpcb.5b05523. Epub 2015 Aug 04.

Phosphatidylglycerol Flip-Flop Suppression due to Headgroup Charge Repulsion.

The journal of physical chemistry. B

Krystal L Brown, John C Conboy

Affiliations

  1. Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84103, United States.

PMID: 26202012 DOI: 10.1021/acs.jpcb.5b05523

Abstract

The kinetics and thermodynamics of 1,2-distearoyl-sn-glycero-3-[phospho(1'-rac-glycerol)] (DSPG) flip-flop in 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) membranes were examined by sum-frequency vibrational spectroscopy (SFVS). The effect of DSPG concentration in the membrane and the influence of electrolyte concentration were examined in an attempt to decipher the role the anionic PG headgroup plays in dictating the dynamics of PG flip-flop for this biologically important lipid species. DSPG flip-flop dynamics and the activation barrier to exchange were found to be directly dependent on the amount of DSPG present in the bilayer. Analysis of the activation free energy for DSPG flip-flop in mixed DSPG + DSPC bilayers reveals that charge repulsion between neighboring PG headgroups modulates the free energy barrier and subsequently, the rate of translocation. Specifically, when DSPG comprises a small portion of the bilayer, the electrostatic potential of neighboring PG lipids are effectively shielded from each other under high ionic strength conditions and little to no charge repulsion occurs. When DSPG lipids are close enough to experience charge repulsion from neighboring PG lipids, as in bilayers containing a large fraction of DSPG, or for bilayers in low ionic strength solutions, the influence of charge repulsion on the energetics of lipid flip-flop are measurable. For biological membranes, where the concentration of PG is relatively low, the neighboring PG lipids are spaced far enough apart that their anionic charges are effectively shielded, such that under physiological conditions the charged nature of the headgroup does little to modulate its lipid flip-flop energetics and corresponding rate of translocation.

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