Analysis of the saturation properties of the in-phase and quadrature second-harmonic ESR spectra of the cholestane spin label in oriented lipid multibilayers in the gel phase

1985 ◽  
Vol 61 (1) ◽  
pp. 1-10
Author(s):  
P Koole ◽  
M.A Hemminga
Keyword(s):  
Spin Label ◽  
Second Harmonic ◽  
Esr Spectra ◽  
Saturation Properties ◽  
Gel Phase ◽  
Cholestane Spin Label

Molecular Motion of the Cholestane Spin Label in a Multibilayer in the Gel Phase Studied Using Echo-Detected EPR

1995 ◽  
Vol 115 (1) ◽  
pp. 80-86 ◽  
Author(s):  
S.A. Dzuba ◽  
H. Watari ◽  
Y. Shimoyama ◽  
A.G. Maryasov ◽  
Y. Kodera ◽  
...  
Keyword(s):  
Spin Label ◽  
Molecular Motion ◽  
Gel Phase ◽  
Cholestane Spin Label

scholarly journals Phase behaviour of DPPC/Lyso-PPC mixtures by spin-label ESR and spectrophotometry

2008 ◽  
Vol 22 (2-3) ◽  
pp. 153-163 ◽  
Author(s):  
Manuela Pantusa ◽  
Luigi Sportelli ◽  
Rosa Bartucci
Keyword(s):  
Spin Label ◽  
Acyl Chain ◽  
Fluid Phase ◽  
Esr Spectra ◽  
Phase Behaviour ◽  
Melting Transition ◽  
Micellar Aggregates ◽  
Lipid Chain ◽  
Main Transition ◽  
Gel Phase

The influence of lysopalmitoylphosphatidylcholine (Lyso-PPC) on lamellar dispersions of dipalmitoylphosphatidylcholine (DPPC) has been investigated by spectrophotometry and electron spin resonance (ESR) of spin-labelled phosphatidylcholine at the C-5 or at the C-16 positions in thesn-2 acyl chain (5- and 16-PCSL). On increasing the concentration of Lyso-PPC up to 10 mol%, the spectral anisotropy of 5-PCSL is slightly reduced whereas that of 16-PCSL is markedly increased. This effect of the lysolipid on the DPPC lipid chain mobility is evident from 10 to 50 mol% at low temperature in the gel phase, disappears in the fluid phase, is associated with the lack of the pre-transition in the mixed lipid dispersions and it is interpreted as interdigitation of the DPPC lipid chains. At intermediate concentrations and for temperatures in the gel phase, the ESR spectra of both labels in DPPC and Lyso-PPC mixtures are the superposition of an anisotropic lamellar component and of an isotropic micellar signal, suggesting the coexistence of lamellar and micellar aggregates. Chain interdigitation and lamellar-micellar coexistence are not evident for temperature above the melting transition temperature. At high Lyso-PPC content (≥60 mol%) the mixed lipid dispersions reach the optical clarity, the main transition is no more detected and spin-label ESR spectra typical of micellar dispersions are detected in the whole temperature range investigated.

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 The liquid-ordered phase in sphingomyelincholesterol membranes as detected by the discrimination by oxygen transport (DOT) method

2008 ◽  
Vol 13 (3) ◽  
Author(s):  
Anna Wisniewska ◽  
Witold Subczynski
Keyword(s):  
Molecular Oxygen ◽  
Oxygen Transport ◽  
Spin Label ◽  
Saturation Recovery ◽  
Transport Parameter ◽  
Dramatic Decrease ◽  
Coexisting Phases ◽  
Liquid Ordered ◽  
Gel Phase ◽  
O Phase

AbstractMembranes made from binary mixtures of egg sphingomyelin (ESM) and cholesterol were investigated using conventional and saturation-recovery EPR observations of the 5-doxylstearic acid spin label (5-SASL). The effects of cholesterol on membrane order and the oxygen transport parameter (bimolecular collision rate of molecular oxygen with the nitroxide spin label) were monitored at the depth of the fifth carbon in fluid- and gel-phase ESM membranes. The saturation-recovery EPR discrimination by oxygen transport (DOT) method allowed the discrimination of the liquid-ordered (l o), liquid-disordered (l d), and solid-ordered (s o) phases because the bimolecular collision rates of the molecular oxygen with the nitroxide spin label differ in these phases. Additionally, oxygen collision rates (the oxygen transport parameter) were obtained in coexisting phases without the need for their separation, which provides information about the internal dynamics of each phase. The addition of cholesterol causes a dramatic decrease in the oxygen transport parameter around the nitroxide moiety of 5-SASL in the l o phase, which at 50 mol% cholesterol becomes ∼5 times smaller than in the pure ESM membrane in the l d phase, and ∼2 times smaller than in the pure ESM membrane in the s o phase. The overall change in the oxygen transport parameter is as large as ∼20-fold. Conventional EPR spectra show that 5-SASL is maximally immobilized at the phase boundary between regions with coexisting l d and l o phases or s o and l o phases and the region with a single l o phase. The obtained results all owed for the construction of a phase diagram for the ESM-cholesterol membrane.

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