LIVIVO - Search results -

Search results

Result 1 - 10 of total 63

Search options

Article: Oxygen Transport Parameter in Plasma Membrane of Eye Lens Fiber Cells by Saturation Recovery EPR.

Stein, N / Subczynski, W K

2020 Volume 52, Issue 1, Page(s) 61–80

Abstract: A probability distribution of rate constants contained within an exponential-like saturation recovery (SR) electron paramagnetic resonance signal can be constructed using stretched exponential function fitting parameters. Previously (Stein et al. ...

Abstract	A probability distribution of rate constants contained within an exponential-like saturation recovery (SR) electron paramagnetic resonance signal can be constructed using stretched exponential function fitting parameters. Previously (Stein et al.
Language	English
Publishing date	2020-08-14
Publishing country	Austria
Document type	Journal Article
ZDB-ID	1480644-7
ISSN	1613-7507 ; 0937-9347
ISSN (online)	1613-7507
ISSN	0937-9347
DOI	10.1007/s00723-020-01237-7
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Details ▾
- Full text online
- Order with fees

Article ; Online: Nitroxide free radicals protect macular carotenoids against chemical destruction (bleaching) during lipid peroxidation.

Zareba, M / Widomska, J / Burke, J M / Subczynski, W K

Free radical biology & medicine

2016 Volume 101, Page(s) 446–454

Abstract: Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including ... ...

Abstract	Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including filtration of phototoxic blue light and quenching of singlet oxygen and triplet states of photosensitizers. These physical protective mechanisms require that MXs be in their intact structure. Here, we investigated the protection of the intact structure of zeaxanthin incorporated into model membranes subjected to oxidative modification by water- and/or membrane-soluble small nitroxide free radicals. Model membranes were formed from saturated, monounsaturated, and polyunsaturated phosphatidylcholines (PCs). Oxidative modification involved autoxidation, iron-mediated, and singlet oxygen-mediated lipid peroxidation. The extent of chemical destruction (bleaching) of zeaxanthin was evaluated from its absorption spectra and compared with the extent of lipid peroxidation evaluated using the thiobarbituric acid assay. Nitroxide free radicals with different polarity (membrane/water partition coefficients) were used. The extent of zeaxanthin bleaching increased with membrane unsaturation and correlated with the rate of PC oxidation. Protection of the intact structure of zeaxanthin by membrane-soluble nitroxides was much stronger than that by water-soluble nitroxides. The combination of zeaxanthin and lipid-soluble nitroxides exerted strong synergistic protection against singlet oxygen-induced lipid peroxidation. The synergistic effect may be explained in terms of protection of the intact zeaxanthin structure by effective scavenging of free radicals by nitroxides, therefore allowing zeaxanthin to quench the primary oxidant, singlet oxygen, effectively by the physical protective mechanism. The redox state of nitroxides was monitored using electron paramagnetic resonance spectroscopy. Both nitroxide free radicals and their reduced form, hydroxylamines, were equally effective. Obtained data were compared with the protective effects of α-tocopherol, which is the natural antioxidant and protector of MXs within the retina. The new strategies employed here to maintain the intact structure of MXs may enhance their protective potential against AMD.
MeSH term(s)	Antioxidants/pharmacology ; Biological Assay ; Electron Spin Resonance Spectroscopy ; Hydrolysis ; Kinetics ; Lipid Peroxidation ; Liposomes/chemistry ; Nitrogen Oxides/chemistry ; Phosphatidylcholines/chemistry ; Solubility ; Thiobarbiturates/chemistry ; Water/chemistry ; Zeaxanthins/pharmacology ; alpha-Tocopherol/pharmacology
Chemical Substances	Antioxidants ; Liposomes ; Nitrogen Oxides ; Phosphatidylcholines ; Thiobarbiturates ; Zeaxanthins ; Water (059QF0KO0R) ; nitroxyl (GFQ4MMS07W) ; alpha-Tocopherol (H4N855PNZ1) ; thiobarbituric acid (M1YZW5SS7C)
Language	English
Publishing date	2016-11-10
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	807032-5
ISSN	1873-4596 ; 0891-5849
ISSN (online)	1873-4596
ISSN	0891-5849
DOI	10.1016/j.freeradbiomed.2016.11.012
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 2109: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Participation of β-carotene in reactivation of PSI of heptane-extracted spinach chloroplasts.

Tukendorf, A / Subczynski, W K / Baszynski, T

Photosynthesis research

2014 Volume 2, Issue 3, Page(s) 153–166

Abstract: A carotenoid requirement for photosystem I activity in spinach chloroplasts using extraction-reconstitution technique has been investigated. The transfer of electron from N,N,N',N'-tetramethyl-p-phenylene diamine through the chloroplast photosystem to ... ...

Abstract	A carotenoid requirement for photosystem I activity in spinach chloroplasts using extraction-reconstitution technique has been investigated. The transfer of electron from N,N,N',N'-tetramethyl-p-phenylene diamine through the chloroplast photosystem to methyl viologen dye or to NADP(+) was used as an assay of photosystem I activity. Extraction of lyophilized spinach chloroplasts with heptane at near 0°C removed almost all β-carotene and reduced photochemical activities associated with photosystem I to a low level (about 15% of the original activity). Reconstitution of the extracted chloroplasts with β-carotene completely restored photosystem I activity. The maximum rate of methyl viologen photoreduction in reconstituted chloroplasts occurred at an β-carotene/chlorophyll molar ratio of 0.5. Cyclic phosphorylation mediated by phenazine methosulphate was partially restored. Xanthophylls (lutein, neoxanthin, violaxanthin), as components of chloroplast membranes, were not able to replace β-carotene in reconstitution of chloroplasts and had essentially no effect on restoring photoreactions. On the basis of the P700/total chlorophyll ratio it can be assumed that extraction of lyophilized chloroplasts with heptane do not affect photosystem I reaction centre. Therefore it is possible that β-carotene, removed during heptane extraction and belonging mainly to the antenna pigment pool of photosystem I, is effective in the restoration of photosystem I activity.
Language	English
Publishing date	2014-01-27
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1475688-2
ISSN	1573-5079 ; 0166-8595
ISSN (online)	1573-5079
ISSN	0166-8595
DOI	10.1007/BF00032354
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

Order via subito

Details ▾
- Full text online
- Order with fees

Article ; Online: Broadband W-band Rapid Frequency Sweep Considerations for Fourier Transform EPR.

Strangeway, Robert A / Hyde, James S / Camenisch, Theodore G / Sidabras, Jason W / Mett, Richard R / Anderson, James R / Ratke, Joseph J / Subczynski, Witold K

Cell biochemistry and biophysics

2017 Volume 75, Issue 3-4, Page(s) 259–273

Abstract: A multi-arm W-band (94 GHz) electron paramagnetic resonance spectrometer that incorporates a loop ...

Abstract	A multi-arm W-band (94 GHz) electron paramagnetic resonance spectrometer that incorporates a loop-gap resonator with high bandwidth is described. A goal of the instrumental development is detection of free induction decay following rapid sweep of the microwave frequency across the spectrum of a nitroxide radical at physiological temperature, which is expected to lead to a capability for Fourier transform electron paramagnetic resonance. Progress toward this goal is a theme of the paper. Because of the low Q-value of the loop-gap resonator, it was found necessary to develop a new type of automatic frequency control, which is described in an appendix. Path-length equalization, which is accomplished at the intermediate frequency of 59 GHz, is analyzed. A directional coupler is favored for separation of incident and reflected power between the bridge and the loop-gap resonator. Microwave leakage of this coupler is analyzed. An oversize waveguide with hyperbolic-cosine tapers couples the bridge to the loop-gap resonator, which results in reduced microwave power and signal loss. Benchmark sensitivity data are provided. The most extensive application of the instrument to date has been the measurement of T
MeSH term(s)	Electron Spin Resonance Spectroscopy/instrumentation ; Electron Spin Resonance Spectroscopy/methods ; Fourier Analysis ; Microwaves ; Signal-To-Noise Ratio
Language	English
Publishing date	2017-05-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	1357904-6
ISSN	1559-0283 ; 1085-9195
ISSN (online)	1559-0283
ISSN	1085-9195
DOI	10.1007/s12013-017-0804-7
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.A 1498: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

Article ; Online: Amounts of phospholipids and cholesterol in lipid domains formed in intact lens membranes: Methodology development and its application to studies of porcine lens membranes.

Raguz, Marija / Mainali, Laxman / O'Brien, William J / Subczynski, Witold K

Experimental eye research

2015 Volume 140, Page(s) 179–186

Abstract: ... L., O'Brien, W.J., and Subczynski, W.K. (2015) Exp. Eye Res.]. Lipids in porcine nuclear fiber ...

Abstract	An electron paramagnetic resonance spin-labeling method has been developed that allows quantitative evaluation of the amounts of phospholipids and cholesterol in lipid domains of intact fiber-cell plasma membranes isolated from cortical and nuclear regions of eye lenses. The long term goal of this research is the assessment of organizational changes in human lens fiber cell membranes that occur with age and during cataract development. The measurements needed to be performed on lens membranes prepared from eyes of single donors and from single eyes. For these types of studies it is necessary to separate the age/cataract related changes from preparation/technique related changes. Human lenses differ not only because of age, but also because of the varying health histories of the donors. To solve these problems the sample-to-sample preparation/technique related changes were evaluated for cortical and nuclear lens membranes prepared from single porcine eyes. It was assumed that the differences due to the age (animals were two year old) and environmental conditions for raising these animals were minimal. Mean values and standard deviations from preparation/technique changes for measured amounts of lipids in membrane domains were calculated. Statistical analysis (Student's t-test) of the data also allowed determining the differences of mean values which were statistically significant with P ≤ 0.05. These differences defined for porcine lenses will be used for comparison of amounts of lipids in domains in human lens membranes prepared from eyes of single donors and from single eyes. Greater separations will indicate that differences were statistically significant with (P ≤ 0.05) and that they came from different than preparation/technique sources. Results confirmed that in nuclear porcine membranes the amounts of lipids in domains created due to the presence of membrane proteins were greater than those in cortical membranes and the differences were larger than the differences observed for human intact fiber cell membranes [Raguz, M. Mainali, L., O'Brien, W.J., and Subczynski, W.K. (2015) Exp. Eye Res.]. Lipids in porcine nuclear fiber cell plasma membranes were more rigid and less permeable to oxygen than in human nuclear membranes. Most likely the significant differences in the lipid composition were responsible for the observed differences.
MeSH term(s)	Animals ; Cell Membrane/metabolism ; Cholesterol/metabolism ; Electron Spin Resonance Spectroscopy ; Humans ; Hydrophobic and Hydrophilic Interactions ; Lens Cortex, Crystalline/metabolism ; Lens Nucleus, Crystalline/metabolism ; Lipid Bilayers/metabolism ; Membrane Lipids/metabolism ; Oxygen/metabolism ; Phospholipids/metabolism ; Spin Labels ; Sus scrofa
Chemical Substances	Lipid Bilayers ; Membrane Lipids ; Phospholipids ; Spin Labels ; Cholesterol (97C5T2UQ7J) ; Oxygen (S88TT14065)
Language	English
Publishing date	2015-11
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	80122-7
ISSN	1096-0007 ; 0014-4835
ISSN (online)	1096-0007
ISSN	0014-4835
DOI	10.1016/j.exer.2015.09.006
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 163: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Using spin-label W-band EPR to study membrane fluidity profiles in samples of small volume.

Mainali, Laxman / Hyde, James S / Subczynski, Witold K

Journal of magnetic resonance (San Diego, Calif. : 1997)

2012 Volume 226, Page(s) 35–44

Abstract: ... Mainali, J.B. Feix, J.S. Hyde, W.K. Subczynski, J. Magn. Reson. 212 (2011) 418-425). Profiles of the spin ... Conventional and saturation-recovery (SR) EPR at W-band (94GHz) using phosphatidylcholine ... on phospholipid headgroups. EPR at W-band provides more detailed information about the depth-dependent dynamic ...

Abstract	Conventional and saturation-recovery (SR) EPR at W-band (94GHz) using phosphatidylcholine spin labels (labeled at the alkyl chain [n-PC] and headgroup [T-PC]) to obtain profiles of membrane fluidity has been demonstrated. Dimyristoylphosphatidylcholine (DMPC) membranes with and without 50 mol% cholesterol have been studied, and the results have been compared with similar studies at X-band (9.4 GHz) (L. Mainali, J.B. Feix, J.S. Hyde, W.K. Subczynski, J. Magn. Reson. 212 (2011) 418-425). Profiles of the spin-lattice relaxation rate (T(1)(-1)) obtained from SR EPR measurements for n-PCs and T-PC were used as a convenient quantitative measure of membrane fluidity. Additionally, spectral analysis using Freed's MOMD (microscopic-order macroscopic-disorder) model (E. Meirovitch, J.H. Freed J. Phys. Chem. 88 (1984) 4995-5004) provided rotational diffusion coefficients (R(perpendicular) and R(\|\|)) and order parameters (S(0)). Spectral analysis at X-band provided one rotational diffusion coefficient, R(perpendicular). T(1)(-1), R(perpendicular), and R(\|\|) profiles reflect local membrane dynamics of the lipid alkyl chain, while the order parameter shows only the amplitude of the wobbling motion of the lipid alkyl chain. Using these dynamic parameters, namely T(1)(-1), R(perpendicular), and R(\|\|), one can discriminate the different effects of cholesterol at different depths, showing that cholesterol has a rigidifying effect on alkyl chains to the depth occupied by the rigid steroid ring structure and a fluidizing effect at deeper locations. The nondynamic parameter, S(0), shows that cholesterol has an ordering effect on alkyl chains at all depths. Conventional and SR EPR measurements with T-PC indicate that cholesterol has a fluidizing effect on phospholipid headgroups. EPR at W-band provides more detailed information about the depth-dependent dynamic organization of the membrane compared with information obtained at X-band. EPR at W-band has the potential to be a powerful tool for studying membrane fluidity in samples of small volume, ~30 nL, compared with a representative sample volume of ~3 μL at X-band.
MeSH term(s)	Cholesterol/chemistry ; Dimyristoylphosphatidylcholine/chemistry ; Electron Spin Resonance Spectroscopy/methods ; Indicators and Reagents ; Membrane Fluidity/physiology ; Phosphatidylcholines/chemistry ; Phospholipids/chemistry ; Spin Labels
Chemical Substances	Indicators and Reagents ; Phosphatidylcholines ; Phospholipids ; Spin Labels ; Cholesterol (97C5T2UQ7J) ; Dimyristoylphosphatidylcholine (U86ZGC74V5)
Language	English
Publishing date	2012-11-12
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	1469665-4
ISSN	1096-0856 ; 1557-8968 ; 1090-7807 ; 0022-2364
ISSN (online)	1096-0856 ; 1557-8968
ISSN	1090-7807 ; 0022-2364
DOI	10.1016/j.jmr.2012.11.001
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Article ; Online: Lipid-protein interactions in plasma membranes of fiber cells isolated from the human eye lens.

Raguz, Marija / Mainali, Laxman / O'Brien, William J / Subczynski, Witold K

Experimental eye research

2014 Volume 120, Page(s) 138–151

Abstract: ... O'Brien, W. J., and Subczynski, W. K. (2013) Biochim. Biophys. Acta]. Differences were considered to be ...

Abstract	The protein content in human lens membranes is extremely high, increases with age, and is higher in the nucleus as compared with the cortex, which should strongly affect the organization and properties of the lipid bilayer portion of intact membranes. To assess these effects, the intact cortical and nuclear fiber cell plasma membranes isolated from human lenses from 41- to 60-year-old donors were studied using electron paramagnetic resonance spin-labeling methods. Results were compared with those obtained for lens lipid membranes prepared from total lipid extracts from human eyes of the same age group [Mainali, L., Raguz, M., O'Brien, W. J., and Subczynski, W. K. (2013) Biochim. Biophys. Acta]. Differences were considered to be mainly due to the effect of membrane proteins. The lipid-bilayer portions of intact membranes were significantly less fluid than lipid bilayers of lens lipid membranes, prepared without proteins. The intact membranes were found to contain three distinct lipid environments termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain. However, the cholesterol bilayer domain, which was detected in cortical and nuclear lens lipid membranes, was not detected in intact membranes. The relative amounts of bulk and trapped lipids were evaluated. The amount of lipids in domains uniquely formed due to the presence of membrane proteins was greater in nuclear membranes than in cortical membranes. Thus, it is evident that the rigidity of nuclear membranes is greater than that of cortical membranes. Also the permeability coefficients for oxygen measured in domains of nuclear membranes were significantly lower than appropriate coefficients measured in cortical membranes. Relationships between the organization of lipids into lipid domains in fiber cells plasma membranes and the organization of membrane proteins are discussed.
MeSH term(s)	Adult ; Cell Membrane/metabolism ; Electron Spin Resonance Spectroscopy ; Humans ; Lens, Crystalline/cytology ; Lens, Crystalline/metabolism ; Lipids/analysis ; Membrane Lipids/metabolism ; Membrane Proteins/metabolism ; Middle Aged ; Spin Labels ; Tissue Donors
Chemical Substances	Lipids ; Membrane Lipids ; Membrane Proteins ; Spin Labels
Language	English
Publishing date	2014-01-31
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	80122-7
ISSN	1096-0007 ; 0014-4835
ISSN (online)	1096-0007
ISSN	0014-4835
DOI	10.1016/j.exer.2014.01.018
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 163: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Spin-label oximetry at Q- and W-band.

Subczynski, W K / Mainali, L / Camenisch, T G / Froncisz, W / Hyde, J S

Journal of magnetic resonance (San Diego, Calif. : 1997)

2011 Volume 209, Issue 2, Page(s) 142–148

Abstract: ... Hyde, et al., J. Phys. Chem. B 108 (2004) 9524-9529). The T₁s measured at W-band (94 GHz ... however, shorter than when measured at Q-band (35 GHz). In this paper, the decreasing trends at W-band have been ... This contribution is expressed in terms of the oxygen transport parameter W=T₁⁻¹(Air)-T₁⁻¹(N₂), which is a function ...

Abstract	Spin-lattice relaxation times (T₁s) of small water-soluble spin-labels in the aqueous phase as well as lipid-type spin-labels in membranes increase when the microwave frequency increases from 2 to 35 GHz (Hyde, et al., J. Phys. Chem. B 108 (2004) 9524-9529). The T₁s measured at W-band (94 GHz) for the water-soluble spin-labels CTPO and TEMPONE (Froncisz, et al., J. Magn. Reson. 193 (2008) 297-304) are, however, shorter than when measured at Q-band (35 GHz). In this paper, the decreasing trends at W-band have been confirmed for commonly used lipid-type spin-labels in model membranes. It is concluded that the longest values of T₁ will generally be found at Q-band, noting that long values are advantageous for measurement of bimolecular collisions with oxygen. The contribution of dissolved molecular oxygen to the relaxation rate was found to be independent of microwave frequency up to 94 GHz for lipid-type spin-labels in membranes. This contribution is expressed in terms of the oxygen transport parameter W=T₁⁻¹(Air)-T₁⁻¹(N₂), which is a function of both concentration and translational diffusion of oxygen in the local environment of a spin-label. The new capabilities in measurement of the oxygen transport parameter using saturation-recovery (SR) EPR at Q- and W-band have been demonstrated in saturated (DMPC) and unsaturated (POPC) lipid bilayer membranes with the use of stearic acid (n-SASL) and phosphatidylcholine (n-PC) spin-labels, and compared with results obtained earlier at X-band. SR EPR spin-label oximetry at Q- and W-band has the potential to be a powerful tool for studying samples of small volume, ~30 nL. These benefits, together with other factors such as a higher resonator efficiency parameter and a new technique for canceling free induction decay signals, are discussed.
MeSH term(s)	Electron Spin Resonance Spectroscopy ; Lipid Bilayers/chemistry ; Lipids/chemistry ; Liposomes/chemistry ; Membranes, Artificial ; Microwaves ; Nitrogen Oxides/chemistry ; Oximetry/methods ; Oxygen/chemistry ; Phosphatidylcholines/chemistry ; Reactive Oxygen Species/chemistry ; Spin Labels ; Stearic Acids/chemistry
Chemical Substances	Lipid Bilayers ; Lipids ; Liposomes ; Membranes, Artificial ; Nitrogen Oxides ; Phosphatidylcholines ; Reactive Oxygen Species ; Spin Labels ; Stearic Acids ; stearic acid (4ELV7Z65AP) ; Oxygen (S88TT14065) ; 1-palmitoyl-2-oleoylphosphatidylcholine (TE895536Y5)
Language	English
Publishing date	2011-01-08
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	1469665-4
ISSN	1096-0856 ; 1557-8968 ; 1090-7807 ; 0022-2364
ISSN (online)	1096-0856 ; 1557-8968
ISSN	1090-7807 ; 0022-2364
DOI	10.1016/j.jmr.2011.01.003
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Article: Spin-label W-band EPR with seven-loop-six-gap resonator: Application to lens membranes derived from eyes of a single donor.

Mainali, Laxman / Sidabras, Jason W / Camenisch, Theodore G / Ratke, Joseph J / Raguz, Marija / Hyde, James S / Subczynski, Witold K

Applied magnetic resonance

2014 Volume 45, Issue 12, Page(s) 1343–1358

Abstract: ... to study membrane properties (L. Mainali, J.S. Hyde, W.K. Subczynski, Using spin-label W-band EPR to study ... Spin-label W-band (94 GHz) EPR with a five-loop-four-gap resonator (LGR) was successfully applied ... than the sensitive volume of the LGR and transferred to the resonator in a quartz capillary. A seven-loop-six-gap W ...

Abstract	Spin-label W-band (94 GHz) EPR with a five-loop-four-gap resonator (LGR) was successfully applied to study membrane properties (L. Mainali, J.S. Hyde, W.K. Subczynski, Using spin-label W-band EPR to study membrane fluidity in samples of small volume, J. Magn. Reson. 226 (2013) 35-44). In that study, samples were equilibrated with the selected gas mixture outside the resonator in a sample volume ~100 times larger than the sensitive volume of the LGR and transferred to the resonator in a quartz capillary. A seven-loop-six-gap W-band resonator has been developed. This resonator permits measurements on aqueous samples of 150 nL volume positioned in a polytetrafluoroethylene (PTFE) gas permeable sample tube. Samples can be promptly deoxygenated or equilibrated with an air/nitrogen mixture inside the resonator, which is significant in saturation-recovery measurements and in spin-label oximetry. This approach was tested for lens lipid membranes derived from lipids extracted from two porcine lenses (single donor). Profiles of membrane fluidity and the oxygen transport parameter were obtained from saturation-recovery EPR using phospholipid analog spin-labels. Cholesterol analog spin-labels allowed discrimination of the cholesterol bilayer domain and acquisition of oxygen transport parameter profiles across this domain. Results were compared with those obtained previously for membranes derived from a pool of 100 lenses. Results demonstrate that EPR at W-band can be successfully used to study aqueous biological samples of small volume under controlled oxygen concentration.
Language	English
Publishing date	2014-12-05
Publishing country	Austria
Document type	Journal Article
ZDB-ID	1480644-7
ISSN	1613-7507 ; 0937-9347
ISSN (online)	1613-7507
ISSN	0937-9347
DOI	10.1007/s00723-014-0578-7
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

Order via subito

Details ▾
- Full text online
- Order with fees

Article: Physical properties of lipid bilayer membranes: relevance to membrane biological functions.

Subczynski, W K / Wisniewska, A

Acta biochimica Polonica

2000 Volume 47, Issue 3, Page(s) 613–625

Abstract: Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is ...

Abstract	Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.
MeSH term(s)	Biological Transport, Active ; Biophysical Phenomena ; Biophysics ; Carotenoids/pharmacology ; Cholesterol/chemistry ; In Vitro Techniques ; Lipid Bilayers/chemistry ; Lipid Bilayers/metabolism ; Membrane Fluidity/drug effects ; Oxygen/metabolism ; Thermodynamics
Chemical Substances	Lipid Bilayers ; Carotenoids (36-88-4) ; Cholesterol (97C5T2UQ7J) ; Oxygen (S88TT14065)
Language	English
Publishing date	2000
Publishing country	Poland
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S. ; Review
ZDB-ID	595762-x
ISSN	1734-154X ; 0001-527X
ISSN (online)	1734-154X
ISSN	0001-527X
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.B 232: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

To top

Full text online

More links

Kategorien

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

Full text online

More links

Kategorien

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito