Liquid Crystalline Samples: Diffusion

Lindblom, Göran; Orädd, Greger

doi:10.1002/9780470034590.emrstm0266

Cited by 2 publications

(3 citation statements)

References 88 publications

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“…The lateral diffusion coefficient of lipids involved in pure membrane bilayers is usually in the range of 10 -7 -10 -8 cm 2 /s. 69,70 In general, a lateral diffusive rate of a lipid on a membrane surface is a function of membrane composition, the concentration of an obstacle, temperature, and hydration level. [71][72][73] Figure 4 shows the influence of lateral diffusions on the line shapes of 31 P (A-D) and 2 H (E-H) SSNMR spectra of phospholipids which take various shapes of elliptic toroidal pores with d ) 0.5b (A, E), 0.7b (B, F), 1.1b (C, G), and 1.3b (D, H), with lateral diffusion coefficients D ld ) 10 -8 , 10 -9 , 10 -10 , 10 -11 , and 10 -12 cm 2 /s.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

“…Under the influence of lipids’ fast lateral diffusive motions ( D ld > 10 −9 cm 2 /s), the anisotropic line shapes of 31 P and 2 H NMR spectra of lipids distributed on a curved surface reflect motional averaging effects, such as line broadening and peak coalescence, when the diffusion rate of lipids exceeds the frequency span of anisotropic frequencies. The lateral diffusion coefficient of lipids involved in pure membrane bilayers is usually in the range of 10 −7 −10 −8 cm 2 /s. , In general, a lateral diffusive rate of a lipid on a membrane surface is a function of membrane composition, the concentration of an obstacle, temperature, and hydration level. − …”

Section: Theoretical Considerationsmentioning

confidence: 99%

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Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Kim

2008

J. Phys. Chem. B

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Membrane pores that are induced in oriented membranes by an antimicrobial peptide (AMP), protegrin-1 (PG-1), are investigated by (31)P and (2)H solid state NMR spectroscopy. We incorporated a well-studied peptide, protegrin-1 (PG-1), a beta-sheet AMP, to investigate AMP-induced dynamic supramolecular lipid assemblies at different peptide concentrations and membrane compositions. Anisotropic NMR line shapes specifying toroidal pores and thinned membranes, which are formed in membrane bilayers by the binding of AMPs, have been analyzed for the first time. Theoretical NMR line shapes of lipids distributed on the surface of toroidal pores and thinned membranes reproduce reasonably well the line shape characteristics of our experimentally measured (31)P and (2)H solid-state NMR spectra of oriented lipids binding with PG-1. The lateral diffusions of lipids are also analyzed from the motionally averaged one- and two-dimensional (31)P and (2)H solid-state NMR spectra of oriented lipids that are binding with AMPs.

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Section: Theoretical Considerationsmentioning

confidence: 99%

Section: Theoretical Considerationsmentioning

confidence: 99%

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Kim

2008

J. Phys. Chem. B

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“…The diffusion coefficients, D L , are related to the radius of curvature, r , and the lateral-diffusion correlation time, τ ld , according to τ ld = r 2 /6 D L . Typical lateral-diffusion coefficients of phospholipids in the liquid-crystalline L α phase are 10 -7 −10 -8 cm 2 /s. , For lipid vesicles with a diameter of 1 μm, which are readily produced by freeze-thawing or extrusion, significant reorientations occur on the time scale of 10−100 ms. Rotations on this time scale can be detected using 2D exchange NMR, where an orientation-dependent frequency is measured at two different times, t 1 and t 2 , separated by a mixing period t m . When molecular reorientations occur during t m , the two frequencies differ.…”

Section: Introductionmentioning

confidence: 99%

Membrane Curvature Change Induced by an Antimicrobial Peptide Detected by ³¹P Exchange NMR

et al. 2005

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The influence of an antimicrobial peptide, protegrin-1 (PG-1), on the curvature and lateral diffusion coefficient (D(L)) of phosphocholine bilayers is investigated using one- (1D) and two-dimensional (2D) (31)P exchange NMR. The experiments utilize the fact that lipid lateral diffusion over the curved surface of vesicles changes the molecular orientation and thus the (31)P chemical shift anisotropy. This reorientation is manifested in 2D spectra as off-diagonal intensities and in 1D stimulated-echo experiments as reduced echo heights. The 2D spectra give information on the reorientation-angle distribution while the decay of the stimulated-echo intensity, which closely tracks the second-order correlation function in our experiments, yields the correlation times of the reorientation. The relationships among the 2D exchange spectra, stimulated-echo intensities, the correlation function, and reorientation-angle distributions are analyzed in detail. In the absence of PG-1, both dilaurylphosphotidylcholine (DLPC) and palmitoyloleoylphosphatidylcholine (POPC) vesicles show biexponential decays of the stimulated-echo intensities to equilibrium values of 0.20-0.25, suggesting that the curvature of the lipid vesicles has a bimodal distribution. The addition of PG-1 to DLPC vesicles increased the decay time constants, indicating that D(L) decreases due to peptide binding. In contrast, the addition of PG-1 to POPC vesicles decreased the decay constants by three to fivefold, indicating that the POPC vesicles are fragmented into smaller vesicles. On the basis of the changes in D(L) and the decay constants, we estimate that the radius of the POPC vesicles decreases by threefold due to PG-1 binding. Simulations of the 2D exchange spectra yielded quantitative reorientation-angle distributions that are consistent with the bimodal distributions of the vesicle curvature and the effects of the peptide on the two types of lipid bilayers. Thus, (31)P exchange NMR provides useful insights into the membrane morphological changes induced by this antimicrobial peptide.

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Liquid Crystalline Samples: Diffusion

Cited by 2 publications

References 88 publications

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Membrane Curvature Change Induced by an Antimicrobial Peptide Detected by ³¹P Exchange NMR

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Liquid Crystalline Samples: Diffusion

Cited by 2 publications

References 88 publications

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: 31P and 2H Solid-State NMR Study

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: 31P and 2H Solid-State NMR Study

Membrane Curvature Change Induced by an Antimicrobial Peptide Detected by 31P Exchange NMR

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Product

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Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Pore Structure, Thinning Effect, and Lateral Diffusive Dynamics of Oriented Lipid Membranes Interacting with Antimicrobial Peptide Protegrin-1: ³¹P and ²H Solid-State NMR Study

Membrane Curvature Change Induced by an Antimicrobial Peptide Detected by ³¹P Exchange NMR