An electron-electron double-resonance study of interactions between [14N]- and [15N]stearic acid spin-label pairs: lateral diffusion and vertical fluctuations in dimyristoylphosphatidylcholine

Feix, Jimmy B.; Popp, Carol A.; Venkataramu, S. D.; Beth, Albert H.; Park, Jane H.; Hyde, James S.

doi:10.1021/bi00305a032

Cited by 64 publications

(64 citation statements)

References 24 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This can be explained by the fact that the end of the DSA chain may squeeze up due to vertical fluctuations. Consequently 16-DSA explores sensibly the same region than does 5-DSA [30][31][32]. Between 10 and 60 mM (Fig.…”

Section: Esr Study Of Sds Aqueous Solutionsmentioning

confidence: 89%

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

Bahri

Hoebeke

Grammenos

et al. 2006

Colloids and Surfaces A: Physicochemical and Engineering Aspect

150

View full text Add to dashboard Cite

Electron spin resonance spectroscopy (ESR) of the nitroxide labelled fatty acid probes (5-, 16-doxyl stearic acid) was used to monitor the micelle microviscosity of three surfactants at various concentrations in aqueous solution: sodium dodecyl sulphate (SDS), dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB). At low surfactant concentration, there is no micelle, the ESR probe is dissolved in water/surfactant homogeneous phase and gives his microviscosity. At higher surfactant concentration, an abrupt increase in microviscosity indicates the apparition of micelles and, the solubilization of the probes in micelles. The microviscosity of the three surfactants, in a large surfactant range, was obtained as well as the critical micelle concentration (CMC). The microviscosity increased slightly with the increase in surfactant concentration. Phosphate buffer lowered the CMC value and generally increased the microviscosity.

show abstract

Section: Esr Study Of Sds Aqueous Solutionsmentioning

confidence: 89%

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

Bahri

Hoebeke

Grammenos

et al. 2006

Colloids and Surfaces A: Physicochemical and Engineering Aspect

150

View full text Add to dashboard Cite

show abstract

“…Dimyristoylphosphatidylcholine (Myr2-PtdCho), and 1-palmitoyl-2-oleoylphosphatidylcholine (Pam-OlePtdCho) were purchased from Avanti Polar Lipids. Multilamellar liposomes were prepared as described previously (13). Stock solutions of lipid components in chloroform were mixed in appropriate amounts to give the desired membrane composition.…”

Section: Methodsmentioning

confidence: 99%

Photodynamic action of merocyanine 540 on artificial and natural cell membranes: involvement of singlet molecular oxygen.

Kalyanaraman¹,

Feix²,

Sieber³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

134

View full text Add to dashboard Cite

The photochemistry of merocyanine 540 (MC 540), a sensitizing dye that binds preferentially to leukemia and electrically excitable cells, has been investigated. MC 540-mediated photooxidation of histidine, arachidonate, and unsaturated phospholipid vesicles was assessed by spin label oximetry and shown to involve type II (singlet oxygen) chemistry. The dye was also shown to be a potent sensitizer of lipid peroxidation in a natural cell membrane, the erythrocyte ghost. Inhibition by azide, stimulation by 2H20, and identification of the cholesterol product 5a-cholest-6-ene-3,8,5-diol in this system, all were consistent with singlet oxygen intermediacy. Finally, MC 540 was found to be considerably more phototoxic to-K-562 leukemia cells in 2H20 than in H20. We conclude that singlet oxygen plays a major role in the phototherapeutic effects of this dye. (4)(5)(6)(7)(8). In this way leukemic cells have been selectively purged from bone marrow in vitro, and attempts to exploit this differential photosensitivity in clinical situations are underway (9).Although the effectiveness of MC 540 in killing neoplastic cells has been demonstrated (5-8), little is known about the mechanism of cell killing, and those factors on which the selectivity of MC 540 for cancer cells is based are not understood. However, the fact that uptake and toxicity of MC 540 in leukemic cells are augmented in the presence of visible light and oxygen (2) suggests that photodynamic processes are involved. A preliminary report has indicated that singlet oxygen (102) is one of the reactive intermediates (10). The first detectable event following the production of this species is rapid consumption of molecular oxygen, which can occur as a result of reactions with biological constituents. Thus, we have used the highly sensitive spin label oximetric approach (11, 12) to monitor oxygen consumption during MC 540-sensitive photooxidation. Using this approach, we now report additional evidence for the production of 102 by the photoactivated dye. The involvement of 102 in the killing of leukemic cells and in the peroxidation of cell membrane phospholipids and cholesterol is also reported. MATERIALS AND METHODSOximetry Studies Using Model Systems. Sample preparation. MC 540 obtained from Eastman was dissolved in a 50:50 mixture of ethanol and water and frozen until further use. Arachidonic acid (Sigma) was dissolved in ethanol. All other chemicals were used as received.Sample irradiation. Samples for irradiation typically contained 90 ,uM MC 540 in deionized water, pH 7.0. 3-Carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy(CTPO; Aldrich) was added to give a final concentration of 1.2 X 10-4 M. Samples, following saturation with a mixture of 50% nitrogen and 50% air from calibrated flow meters (Matheson) were introduced into a Pasteur pipette, which was sealed with capillary tube sealant (Miniseal, American Scientific Products, Stone Mountain, GA) and subsequently positioned inside the electron spin resonance (ESR) cavity.Samples were irradiated in the ES...

show abstract

“…The bimolecular collision rate Wx of species na with species nb is given by Kxnb. Because n2n3 -njn4 = (NII/2)(n2 -nj) + (NI/2)(n3 -n4) [3] where NI and NII are the concentrations of spin systems I and II, respectively (n, + n2 = N1; n3 + n4 = NII), Eqs. 1 and 2 are linear differential equations.…”

mentioning

confidence: 99%

Lateral diffusion of lipids in membranes by pulse saturation recovery electron spin resonance.

Yin¹,

Pasenkiewicz-Gierula²,

Hyde³

1987

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Short-pulse saturation recovery electron spin resonance methods have been used to measure lateral diffusion of nitroxide-labeled lipids in multilamellar liposomal dispersions. Nitroxides with 14N and 15N isotopes introduced both separately and together were used. Differential equations have been written and solved for complex saturation recovery signals involving several superimposed exponentials. The time constants contain various combinations of the spin-lattice relaxation time (Tie) for both isotopes, Heisenberg exchange rates, and nuclear spin-lattice relaxation times (Tln). Signals of high quality were fitted by Monte Carlo variation of the amplitudes and time constants. The reliability of the approach was tested extensively by verifying that (i) the predicted number of exponentials agreed with the experimental number, (ii) relaxation parameters that were determined were independent of the observed hyperfine transition, (iii) the time constants were independent of saturating pulse length, (iv) Tie and TMn do not change when Heisenberg exchange is changed by varying the concentration, and (v) Heisenberg exchange is indeed proportional to the concentration. It has been established that bimolecular collision rates over a wide range of conditions can be reliably measured using the methodology described here. The methods depend on the favorable match of bimolecular collision rates at micromolar concentrations to nitroxide spinlattice relaxation probabilities.For several years we have been developing and applying methodology to measure short-range translational diffusive motions in synthetic and cellular membranes. These methods depend on Heisenberg exchange (HE) between nitroxide radical spin labels; bimolecular collisions between spin labels produce the observed effects. HE results in transfer of saturation between different portions of the spin-label electron spin resonance (ESR) spectrum, and the observed signals arise from this effect. There are two other competing saturation-transfer mechanisms-the nitrogen nuclear spinlattice relaxation characterized by rate Wn, which under certain conditions can be more rapid than the electron spinlattice relaxation rate We, and slow rotational diffusion that causes spectral diffusion of saturation. [Relaxation times T," and Tle are related to these rates by Tl, n = (2Wen)-".I The latter two are intramolecular, and HE is intermolecular §. One might think that HE could readily be distinguished by changing concentrations, but in practical situations the separation of these processes remains an important consideration.Popp and Hyde (1) used steady-state continuous wave electron-electron double resonance (ELDOR) to determine HE rates (Wx) for stearic acid spin labels substituted into dimyristoylphosphatidylcholine (Myr2-PtdCho) liposomal dispersions. The ELDOR experiment gives the ratio of the HE rate to the electron spin-lattice relaxation rate. The latter was determined using the saturation-recovery method. Nuclear spin-lattice relaxation rates were separated by ...

show abstract

An electron-electron double-resonance study of interactions between [14N]- and [15N]stearic acid spin-label pairs: lateral diffusion and vertical fluctuations in dimyristoylphosphatidylcholine

Cited by 64 publications

References 24 publications

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

Photodynamic action of merocyanine 540 on artificial and natural cell membranes: involvement of singlet molecular oxygen.

Lateral diffusion of lipids in membranes by pulse saturation recovery electron spin resonance.

Contact Info

Product

Resources

About