Effects of oxygen on EPR spectra of nitroxide spin-label probes of model membranes

Popp, Carol A.; Hyde, James S.

doi:10.1016/0022-2364(81)90036-6

Cited by 56 publications

(41 citation statements)

References 20 publications

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“…If the system is bubbled with oxygen ( fig.3B), the ESR signal becomes more intense and persistent. Due to the large concentration of oxygen present, the ESR signal exhibits line broadening associated with the interaction of the paramagnetic oxygen with the free radical [17]. The addition of catalase to the reaction results in a more persistent radical signal ( fig.3C).…”

Section: Resultsmentioning

confidence: 99%

The enzymatic oxidation of Desferal to a nitroxide free radical

1987

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Desferrioxamine mesylate (Desferal), a transition metal ion chelator, has been used to inhibit the in vitro redox cycling of transition metal ions. ESR spectroscopy was utilized to detect and identify Desferal's oneelectron oxidation product. We demonstrate that a horseradish peroxidase/H202 system, a xanthine oxidase/hypoxanthine system, and a hydroxyl radical-generating system are all capable of oxidizing Desferal to a nitroxide free radical. The same 9-line ESR spectrum (g= 2.0065, a N = 7.85 G, an(2)= 6.35 G) was detected in all of the above systems. We, therefore, stress that care must be taken when using Desferal as a transition metal ion chelator to keep its concentration low enough to minimize these reactions, or to use a different metal ion chelator.

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Section: Resultsmentioning

confidence: 99%

The enzymatic oxidation of Desferal to a nitroxide free radical

1987

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“…For oxygen diffusion-concentration product studies, all test samples were run in capillaries made of the methylpentene polymer TPX (0.7 mm i.d). This plastic capillary is permeable to oxygen and nitrogen and is substantially impermeable to water (37). The TPX capillary was placed inside the ESR Dewar insert and equilibrated with a flow of various gases (nitrogen, oxygen, or air) which were also used for temperature control.…”

mentioning

confidence: 99%

Effects of conjugated linoleic acid on oxygen diffusion‐concentration product and depletion in membranes by using electron spin resonance spin‐label oximetry

Yin

Mossoba

Kramer

et al. 1999

Lipids

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The effect of conjugated linoleic acid (CLA) on the relation between structure and function of membranes is described in this paper. Electron spin resonance (ESR) spin-label oximetry was used in the present study to evaluate if oxygen transport and oxygen depletion were affected by incorporation of CLA instead of linoleic acid into membrane phospholipids. Specifically, 1-stearoyl-2-(9cis, 11 trans-octadecadienoyl)-phosphorylcholine (SCLAPC) was incorporated into soy plant phosphatidylcholine (soy PC) or egg yolk PC (EYPC) bilayers. The use of spin labels attached to different carbons along the fatty acid chain makes it possible to carry out structural and oximetric determinations with the same test sample. For example, the incorporation of 5 mol% SCLAPC increased the oxygen diffusion-concentration product in soy PC or EYPC liposomes at 37 degrees C, slightly decreased the ordering of the hydrocarbon chains at the C10 and C12 positions (in the region of the conjugated double bonds), and increased the rate of oxygen depletion from the aqueous medium. Similar results were not obtained by incorporating 5 mol% of 1-stearoyl-2-linoleoyl-PC (SLPC). In our model system, free-radical generation was initiated by extended incubation of the liposomes, by induction by 2,2'-azobis(2-amidinopropane)hydrochloride, or by ultraviolet irradiation of H2O2. The rate of consumption of molecular oxygen was studied by monitoring the oxygen concentration in the aqueous phases of the liposomes. The effect of 5 mol% SCLAPC in soy PC was significantly larger than 5 mol% SLPC in soy PC; the response patterns with soy PC and EYPC were similar. Furthermore, 5 mol% SCLAPC in 1-palmitoyl-2-linoleoyl-PC showed similar oxygen consumption to that observed with 5 mol% SCLAPC in EYPC. On the other hand, 5 mol% SCLAPC in synthetic PC membranes containing saturated or monounsaturated fatty acids showed low oxygen depletion rates. The perturbation of membrane structure and the increase of the relative oxygen diffusion-concentration products provided a potential mechanism by which CLA incorporated into membrane lipids could affect oxidative stress.

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“…EPR oximetry, first reported by Hyde [1] and later extensively investigated by Swartz and colleagues [2][3][4][5], enables repeated measurements of oxygen concentrations in living tissues. In vivo oximetry [6][7][8][9] is the measurement of partial pressure of oxygen (pO 2 ) by observing oxygen-induced broadening in the lineshape of an introduced paramagnetic probe.…”

Section: Epr Oximetrymentioning

confidence: 99%

EPR oximetry in three spatial dimensions using sparse spin distribution

Som

Potter

Ahmad

et al. 2008

Journal of Magnetic Resonance

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A method is presented to use continuous wave electron paramagnetic resonance imaging for rapid measurement of oxygen partial pressure in three spatial dimensions. A particulate paramagnetic probe is employed to create a sparse distribution of spins in a volume of interest. Information encoding location and spectral linewidth is collected by varying the spatial orientation and strength of an applied magnetic gradient field. Data processing exploits the spatial sparseness of spins to detect voxels with nonzero spin and to estimate the spectral linewidth for those voxels. The parsimonious representation of spin locations and linewidths permits an order of magnitude reduction in data acquisition time, compared to four-dimensional tomographic reconstruction using traditional spectral-spatial imaging. The proposed oximetry method is experimentally demonstrated for a lithium octa-n-butoxy naphthalocyanine (LiNc-BuO) probe using an L-band EPR spectrometer.

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Effects of oxygen on EPR spectra of nitroxide spin-label probes of model membranes

Cited by 56 publications

References 20 publications

The enzymatic oxidation of Desferal to a nitroxide free radical

The enzymatic oxidation of Desferal to a nitroxide free radical

Effects of conjugated linoleic acid on oxygen diffusion‐concentration product and depletion in membranes by using electron spin resonance spin‐label oximetry

EPR oximetry in three spatial dimensions using sparse spin distribution

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