An NMR study of the origin of dioxygen-induced spin-lattice relaxation enhancement and chemical shift perturbation

Prosser, R. Scott; Luchette, Paul

doi:10.1016/j.jmr.2004.08.012

Cited by 20 publications

(14 citation statements)

References 23 publications

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“…So the oxygen effect is the most apparent factor to consider when comparing to the literature. It is well known that paramagnetic oxygen dissolved in solutions causes a major shortening of T 1 relaxation times 14–19. To see the specific oxygen effect on our samples, we degassed the EO‐5 copolymer solution by subjecting it to three freeze–pump–thaw cycles before sealing the NMR tube.…”

Section: Resultsmentioning

confidence: 99%

Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane

Qiu

Zhou

2010

Magnetic Reson in Chemistry

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'Unexpected' proton spin-lattice relaxation (T(1)) times are reported for the solutions of poly(ethylene-co-1-octene) and tetrachloroethane-d(2). For the residual protons of the deuterated solvent and the methyl and vinyl protons at the polymer chain ends, their T(1) relaxation times vary significantly with both the polymer concentration and molecular weight over a wide range. The T(1)s also decrease with increasing temperature at relative high temperatures. Such behaviors are in contrast to most reported polymer solutions in which the T(1) has nearly no concentration or molecular weight dependence in the dilute and semi-dilute regime, and normal dependence on temperature. Further investigation revealed that the paramagnetic oxygen effect did shorten the measured proton T(1)s, but cannot account for the unexpected T(1) dependences. Spin rotation is proposed to provide a reasonable explanation.

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Section: Resultsmentioning

confidence: 99%

Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane

Qiu

Zhou

2010

Magnetic Reson in Chemistry

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“…Measurable 13 C paramagnetic shifts (roughly 0.4 ppm or less) at oxygen partial pressures of 30 and 60 bar were also reported and interpreted in terms of protein structure and solvent exposure. At such partial pressures, line broadening is relatively weak while the shifts, which have been previously attributed to a contact mechanism (15), are sufficiently small that assignments are straightforward to make, particularly if spectra are recorded as a function of oxygen partial pressure.…”

Section: The Effect Of Dissolved Oxygen On Chemical Shiftsmentioning

confidence: 90%

Molecular oxygen as a paramagnetic NMR probe of protein solvent exposure and topology

Bezsonova

Forman‐Kay

Prosser

2008

Concepts Magnetic Resonance

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This review focuses on the applications of dissolved oxygen in NMR studies of protein topology. A brief discussion is given to explain the origin of O 2 -induced paramagnetic shifts and relaxation rate enhancements, which are seen for a variety of nuclei of biological interest-in particular 13 C, 19 F, and 1 H. We also give examples of applications of paramagnetic effects from dissolved O 2 , which include studies of solvent exposure, hydrophobicity, transient contacts or local clustering in intrinsically disordered proteins, immersion depth in membranous systems, and topology of membrane proteins.

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“…In the present case, our goal is to directly measure local effects of oxygen in a lipid bilayer without the use of any probe molecule. We observe that modest partial pressures (50 atm) are sufficient to observe significant 13 C NMR paramagnetic shifts, which we attribute to a contact mechanism (31). Contact shifts, which arise from unpaired electron spin density at the resonant nucleus, are typically awkward to compute or interpret in terms of structural information (32,33).…”

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confidence: 81%

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

Al‐Abdul‐Wahid

Batruch

et al. 2006

Biochemistry

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The transmembrane profile of oxygen solubility and diffusivity in a lipid bilayer was assessed by (13)C 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 50 atm, distinct chemical shift perturbations of a paramagnetic origin were observed, spanning a factor of 3.2 within the sn-1 chain and an overall factor of 10 from the headgroup to the hydrophobic interior. The distinguishing feature of the (13)C NMR shift perturbation measurements, in comparison to ESR and fluorescence quenching measurements, is that the local accessibility of oxygen is achieved for nearly all carbon atoms in a single experiment with atomic resolution and without the use of a probe molecule. MD simulations of an oxygenated and hydrated lipid bilayer provided an immersion depth distribution of all carbon nuclei, in addition to the distribution of oxygen concentration and diffusivity with immersion depth. All oxygen-induced (13)C NMR chemical shift perturbations could be reasonably approximated by simply accounting for the MD-derived immersion depth distribution of oxygen in the bilayer, appropriately averaged according to the immersion depth distribution of the (13)C nuclei. Second-order effects in the paramagnetic shift are attributed to the collisionally accessible solid angle or to the propensity of the valence electrons in the vicinity of a given nuclear spin to be polarized or delocalized by oxygen. A method is presented to measure such effects. The excellent agreement between MD and NMR provides an important cross-validation of the two techniques.

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An NMR study of the origin of dioxygen-induced spin-lattice relaxation enhancement and chemical shift perturbation

Cited by 20 publications

References 23 publications

Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane

Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane

Molecular oxygen as a paramagnetic NMR probe of protein solvent exposure and topology

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

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