A Combined NMR and Molecular Dynamics Study of the Transmembrane Solubility and Diffusion Rate Profile of Dioxygen in Lipid Bilayers

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• 作者：M. Sameer Al-Abdul-Wahid ; Ching-Hsing Yu ; Ihor Batruch ; Ferenc Evanics ; Ré ; gis Pom&egrave ; s ; R. Scott Prosser
• 刊名：Biochemistry
• 出版年：2006
• 出版时间：September 5, 2006
• 年：2006
• 卷：45
• 期：35
• 页码：10719 - 10728
• 全文大小：146K
• 年卷期：v.45,no.35(September 5, 2006)
• ISSN：1520-4995

文摘

The transmembrane profile of oxygen solubility and diffusivity in a lipid bilayer was assessedby ¹³C NMR of the resident lipids (sn-2-perdeuterio-1-myristelaidoyl-2-myristoyl-sn-glycero-3-phosphocholine) in combination with molecular dynamics (MD) simulations. At an oxygen partial pressure of 50atm, distinct chemical shift perturbations of a paramagnetic origin were observed, spanning a factor of3.2 within the sn-1 chain and an overall factor of 10 from the headgroup to the hydrophobic interior. Thedistinguishing feature of the ¹³C NMR shift perturbation measurements, in comparison to ESR andfluorescence quenching measurements, is that the local accessibility of oxygen is achieved for nearly allcarbon atoms in a single experiment with atomic resolution and without the use of a probe molecule. MDsimulations of an oxygenated and hydrated lipid bilayer provided an immersion depth distribution of allcarbon nuclei, in addition to the distribution of oxygen concentration and diffusivity with immersiondepth. All oxygen-induced ¹³C NMR chemical shift perturbations could be reasonably approximated bysimply accounting for the MD-derived immersion depth distribution of oxygen in the bilayer, appropriatelyaveraged according to the immersion depth distribution of the ¹³C nuclei. Second-order effects in theparamagnetic shift are attributed to the collisionally accessible solid angle or to the propensity of thevalence electrons in the vicinity of a given nuclear spin to be polarized or delocalized by oxygen. Amethod is presented to measure such effects. The excellent agreement between MD and NMR providesan important cross-validation of the two techniques.