scholarly journals Organization of membrane lipids and proteins in human En(a-) erythrocytes that lack the major sialoglycoprotein, glycophorin A. A spin-label study

1981 ◽  
Vol 195 (1) ◽  
pp. 123-128 ◽  
Author(s):  
S E Jansson ◽  
J Gripenberg ◽  
R Hekali ◽  
C G Gahmberg
Keyword(s):  
Stearic Acid ◽  
Membrane Fluidity ◽  
Membrane Lipids ◽  
Spin Labels ◽  
Glycophorin A ◽  
Hydrophobic Core ◽  
Protein Motion ◽  
Normal Cells ◽  
Label Study ◽  
Spin Resonance

Membrane fluidity was studied by electron-spin-resonance techniques in human En(a-) erythrocytes that lack the major membrane sialoglycoprotein, glycophorin A. By using stearic acid spin labels with a doxyl group in the C-12 or C-15 positions, we demonstrated that the hydrophobic core in these cells was more fluid than in normal cells. Surface-located regions in isolated En(a-) membranes, when probed with stearic acid labelled in the C-5 position, appeared more stable than in normal membranes. In isolated En(a-) membranes, protein motion was decreased when probed with a nitroxide derivative of maleimide. After incubation with anti-(glycophorin A) antibodies protein motion and membrane fluidity were increased in normal membranes. This effect was observed also after spectrin depletion, which by itself increased protein motion but decreased membrane fluidity in the hydrophobic core of the membrane. The results show that membrane proteins influence the fluidity of membrane lipids.

scholarly journals Electron Spin Resonance Evaluation of Buccal Membrane Fluidity Alterations by Sodium Caprylate and L-Menthol

2021 ◽  
Vol 22 (19) ◽  
pp. 10708
Author(s):  
Laxmi Shanthi Chede ◽  
Brett A. Wagner ◽  
Garry R. Buettner ◽  
Maureen D. Donovan
Keyword(s):  
Electron Spin Resonance ◽  
Stearic Acid ◽  
Membrane Fluidity ◽  
Electron Spin ◽  
Spin Labels ◽  
Permeation Enhancers ◽  
Head Groups ◽  
Spin Resonance ◽  
Sodium Caprylate ◽  
Membrane Fluidization

The ability of sodium caprylate and l-menthol to fluidize phospholipid bilayers composed of lipids simulating the buccal epithelium was investigated using electron spin resonance (ESR) to evaluate the action of these agents as permeation enhancers. 5-Doxyl stearic acid (5-DSA) and 16-doxyl stearic acid (16-DSA) were used as spin labels to identify alterations in membrane fluidity near the polar head groups or inner acyl regions of the lipid bilayer, respectively. The molecular motion of both 5-DSA and 16-DSA showed increased disorder near the polar and inner hydrophobic regions of the bilayer in the presence of sodium caprylate suggesting fluidization in both the regions, which contributes to its permeation enhancing effects. L-menthol decreased the order parameter for 16-DSA, showing membrane fluidization only in the inner acyl regions of the bilayer, which also corresponded to its weaker permeation enhancing effects. The rapid evaluation of changes in fluidity of the bilayer in the presence of potential permeation enhancers using ESR enables improved selection of effective permeation enhancers and enhancer combinations based on their effect on membrane fluidization.

Intermolecular Steric Interactions and Lipid Chain Fluidity in Phospholipid Multibilayers. A Spin Label Study

1974 ◽  
Vol 52 (7) ◽  
pp. 631-636 ◽  
Author(s):  
D. Marsh
Keyword(s):  
Stearic Acid ◽  
Spin Label ◽  
Spin Labels ◽  
Energy Separation ◽  
Effective Energy ◽  
Label Study ◽  
Steric Interactions ◽  
Egg Lecithin ◽  
Lipid Chain ◽  
Ordered State

The temperature variation of the spectra of stearic acid spin labels has been investigated in oriented egg lecithin multibilayers. The temperature behavior is characterized by an effective value for the energy separation between trans and gauche conformations in the lipid chains. Comparison with bilayers containing cholesterol indicates that this effective energy is sensitive to intermolecular steric interactions. The large value for the effective gauche energy suggests that part of the lipid chains are in a relatively ordered state even in unsaturated lecithin systems.

scholarly journals Changes of Membrane Fluidity in Erythrocytes of Obese Children: A Spin Label Study

1987 ◽  
Vol 22 (2) ◽  
pp. 141-144 ◽  
Author(s):  
Giovanna Curatola ◽  
Gianna Ferretti ◽  
Enrico Bertoli ◽  
Maria Dotti ◽  
Edoardo Bartolotta ◽  
...  
Keyword(s):  
Membrane Fluidity ◽  
Spin Label ◽  
Obese Children ◽  
Label Study

Spin Label Study of Apomembranes and Purple Membranes

1993 ◽  
Vol 48 (5-6) ◽  
pp. 500-503
Author(s):  
Tzvetana R. Lazarova ◽  
Maya Y. Velitchkova
Keyword(s):  
Fatty Acids ◽  
Lipid Bilayer ◽  
Spin Label ◽  
Hyperfine Splitting ◽  
Esr Spectra ◽  
Spin Labels ◽  
Label Study ◽  
Splitting Parameter ◽  
Induced Changes ◽  
Purple Membranes

Abstract Three spin-labelled fatty acids were used to detect the dynamics of lipid bilayer of apomem branes and purple membranes. It was found that ESR spectra of spin labels bound to apo­ membranes showed a temperature-induced changes rather similar to those seen with purple membranes. At the same time, however, the values of hyperfine splitting parameter 2Tm were lower as compared to purple membranes. The results pointed out that the removal of the retinal from purple membranes affects the dynamics of lipid bilayer and apomembranes were more rigid structure than those of purple membranes.

scholarly journals ESR as a monitoring method of the interactions between TEMPO-functionalized magnetic nanoparticles and yeast cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ryszard Krzyminiewski ◽  
Bernadeta Dobosz ◽  
Grzegorz Schroeder ◽  
Joanna Kurczewska
Keyword(s):  
Magnetic Nanoparticles ◽  
Drug Carriers ◽  
Magnetic Core ◽  
Yeast Cells ◽  
Spin Labels ◽  
Monitoring Method ◽  
Functionalized Magnetic Nanoparticles ◽  
Spin Resonance

AbstractPotential application of magnetic nanoparticles as drug carriers in medical treatment requires prior determination of their effects on cells. In this work different spin labels and magnetic nanoparticles functionalized with spin labels as well as their interaction with yeast cells were investigated using electron spin resonance (ESR) method. ESR was demonstrated to be a suitable method for monitoring of magnetic core and attached spin labels. Particular emphasis was placed on characterization of endocytosis and redox processes running inside the cell, resulting in recombination of spin labels. Such data could only be obtained at reduced temperature of ESR measurements.

scholarly journals Membrane fluidity changes accompanying phagocytosis in normal and in chronic granulomatous disease polymorphonuclear leukocytes

Blood ◽  
1981 ◽  
Vol 58 (4) ◽  
pp. 830-835 ◽  
Author(s):  
LM Ingraham ◽  
LA Boxer ◽  
RA Haak ◽  
RL Baehner
Keyword(s):  
Membrane Fluidity ◽  
Polymorphonuclear Leukocytes ◽  
Direct Reduction ◽  
Normal Subjects ◽  
Esr Spectra ◽  
Resting Cells ◽  
Opsonized Zymosan ◽  
Acid Analog ◽  
Spin Resonance ◽  
By Products

Abstract We have studied membrane fluidity changes in polymorphonuclear leukocytes (PMN) during phagocytosis. Membrane fluidity was assessed by electron spin resonance (ESR) using a nitroxide-substituted stearic acid analog (5DS) as a spin probe. PMN from normal subjects and from 3 CGD patients (2 males, 1 female) were incubated in Kreb's Ringers phosphate with or without opsonized zymosan. ESR spectra were obtained and the order parameter (S), which is inversely related to membrane fluidity, was calculated. Without zymosan addition, S for normal (0.638) and for CGD (0.635) were not significantly different (p less than 0.35). The S values indicate that under resting conditions the molecular environment of the CGD membrane is similar to that of normal PMN membranes. However, with addition of opsonized zymosan, the normal, but not the CGD, PMN showed a significant increase (CGD, S = 0.638; normal, S = 0.647; p less than 0.001). This change in S for the normals is consistent with a more restricted movement of 5DS. Treatment of normal PMN with a mixture of scavengers specific for H2O2 (catalase, 1600 U/ml), O2-.(superoxide dismutase, 100 micrograms/ml), and for HO., (sodium benzoate, 1mM) during zymosan stimulation gave S values similar to those of resting cells. Catalase alone also lowered S value, suggesting that H2O2 was instrumental in causing the initial S value increase. This idea was supported by studies in which CGD cells were incubated with zymosan in the presence of glucose oxidase, an enzyme that catalyzes glucose oxidation resulting in the direct reduction of molecular oxygen to H2O2. Our results indicate that reduced O2 by- products, particularly H2O2, can cause altered biophysical properties of PMN membrane during phagocytosis.

Modulation of quorum sensing in Pseudomonas aeruginosa through alteration of membrane properties

Microbiology ◽  
2005 ◽  
Vol 151 (8) ◽  
pp. 2529-2542 ◽  
Author(s):  
Christine Baysse ◽  
Méabh Cullinane ◽  
Valérie Dénervaud ◽  
Elizabeth Burrowes ◽  
J. Maxwell Dow ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Membrane Fluidity ◽  
Environmental Conditions ◽  
Adaptive Response ◽  
Environmental Changes ◽  
Membrane Lipids ◽  
Phospholipid Composition ◽  
Genetically Engineered ◽  
Membrane Properties

Changes in the cellular envelope are major physiological adaptations that occur when micro-organisms encounter extreme environmental conditions. An appropriate degree of membrane fluidity is crucial for survival, and alteration of membrane lipids is an essential adaptive response. Emerging data suggest that microbial cells may recognize alterations in their membrane viscosity resulting from certain environmental changes as a trigger for adaptive cellular responses. In Pseudomonas aeruginosa, the quorum-sensing (QS) system involves a complex regulatory circuitry that coordinates the expression of genes according to a critical population density. Interestingly, it has been shown that the QS system of P. aeruginosa can also be activated by nutritional stress, independently of the cell density, and therefore may be part of a more general adaptive response to stressful environmental conditions. In order to examine the proposed link between membrane properties and stress signalling, the effects of genetically engineered alterations of the membrane phospholipid composition of P. aeruginosa PAO1 on the activation of the stringent response and the QS system were examined. The lptA gene encoding a functional homologue of PlsC, an Escherichia coli enzyme that catalyses the second step of the phospholipid biosynthesis pathway, was identified and disrupted. Inactivation of lptA altered the fatty acid profile of phospholipids and the membrane properties, resulting in decreased membrane fluidity. This resulted in a premature production of the QS signals N-butanoyl- and N-hexanoyl-homoserine lactone (C4-HSL and C6-HSL) and a repression of 2-heptyl-3-hydroxy-4-quinolone (PQS) synthesis at later growth phases. The effects on C4- and C6-HSL depended upon the expression of relA, encoding the (p)ppGpp alarmone synthase, which was increased in the lptA mutant. Together, the findings support the concept that alterations in membrane properties can act as a trigger for stress-related gene expression.

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