Main text
(Biophysical Journal 112, 2336–2347; June 6, 2017)
In Figure 4 of the article, the O2 concentration curve reproduced from reference 53 should be labeled as deriving from a molecular dynamics simulation rather than from an NMR experiment. Reference 53 reports both experimental and atomistic molecular dynamics simulation datasets, showing strong agreement between simulation-based O2 concentration data and O2-induced 13C NMR paramagnetic shifts. A follow-up study led by the same researchers provides an estimated NMR-based O2 concentration profile along the bilayer depth, derived through multiplication of experimental O2-induced paramagnetic shifts by a constant scaling factor determined through fitting to molecular dynamics simulation data (Al-Abdul-Wahid, M.S., F. Evanics, and R.S. Prosser. 2011. Dioxygen transmembrane distributions and partitioning thermodynamics in lipid bilayers and micelles. Biochemistry. 50:3975–3983).
The corrected Figure 4, shown below with a corrected legend, compares the resulting NMR-based oxygen concentration profile (black squares) with our POPC simulation curve originally included in Figure 4 of the article (blue line). The NMR-based curve shows “dips” in the headgroup region (±16–20 Å, relative to the bilayer center), consistent with those visible in the POPC simulation-based curve (near ±22 Å). Comparison of lipid-water partitioning for the two datasets suggests that our simulation O2 model exaggerates O2 partitioning by nearly a factor of 3, consistent with the analysis in the article. The conclusions of the article are not altered by the figure correction.
Minor tweaks to the simulation O2 force-field parameters have enabled reduction of the exaggerated lipid-water partitioning and updated estimation of cholesterol effects on oxygen permeability: Dotson, R.J., E. McClenahan, and S.C. Pias. 2021. Updated evaluation of cholesterol’s influence on membrane oxygen permeability. Adv. Exp. Med. Biol. 1269:23–30.
Figure 4. Comparison with NMR data supports the accuracy of the O2 concentration curve shape
A single simulation POPC curve (blue line) is overlaid with an NMR-based curve for the phospholipid MLMPC at 45°C (black squares). The NMR-based dataset is reproduced from the following reference: Al-Abdul-Wahid, M.S., F. Evanics, and R.S. Prosser. 2011. Dioxygen transmembrane distributions and partitioning thermodynamics in lipid bilayers and micelles. Biochemistry. 50:3975–3983. To facilitate visual comparison, the scale of the simulation curve has been matched to that of the NMR-based dataset near the bilayer center. To see this figure in color, go online.