Effect of orientational order on the decay of the fluorescence anisotropy in membrane suspensions. A new approximate solution of the rotational diffusion equation

Meer, W. van der; Pottel, Hans; Herreman, W.; Ameloot, Marcel; Hendrickx, H; Schröder, H.

doi:10.1016/s0006-3495(84)84049-7

Cited by 128 publications

(61 citation statements)

References 11 publications

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“…In the case of a prolate ellipsoidal body fluctuating in a strong ordering potential, a description that holds well for side-chain movements in a protein, the diffusion coefficient for wobbling motions of the long axis is given by D Ќ ϭ ͗ 2 ͘͞2 with the mean-square amplitude (39). The orientational fluctuations of a protein, therefore, can be described in terms of diffusional coefficients D and (root-mean-square) angular amplitudes .…”

Section: Methodsmentioning

confidence: 99%

Interaction between HLA-DM and HLA-DR involves regions that undergo conformational changes at lysosomal pH

Ullrich

Döring

Grüneberg

et al. 1997

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

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Antigenic peptide loading of major histocompatibility complex class II molecules is enhanced by lysosomal pH and catalyzed by the HLA-DM molecule. The physical mechanism behind the catalytic activity of DM was investigated by using time-resolved f luorescence anisotropy (TRFA) and f luorescence binding studies with the dye 8-anilino-1-naphthalenesulfonic acid (ANS). We demonstrate that the conformations of both HLA-DM and HLA-DR3, irrespective of the composition of bound peptide, are pH sensitive. Both complexes reversibly expose more nonpolar regions upon protonation. Interaction of DM with DR shields these hydrophobic domains from the aqueous environment, leading to stabilization of the DM and DR conformations. At lysosomal pH, the uncovering of additional hydrophobic patches leads to a more extensive DM-DR association. We propose that DM catalyzes class II peptide loading by stabilizing the low-pH conformation of DR, favoring peptide exchange. The DM-DR association involves a larger hydrophobic surface area with DR͞class II-associated invariant chain peptides (CLIP) than with stable DR͞peptide complexes, explaining the preferred association of DM with the former. The data support a release mechanism of DM from the DM-DR complex through reduction of the interactive surface, upon binding of class II molecules with antigenic peptide or upon neutralization of the DM-DR complex at the cell surface.Presentation of peptides derived from exogenous proteins predominantly occurs in the context of heterodimeric major histocompatibility complex (MHC) class II molecules (1). Binding of these peptides probably takes place in specialized intracellular vesicles, called MHC class II compartments (MIICs; ref. 2). Class II molecules are directed to the MIICs after dimerization in the endoplasmic reticulum and complexing to the invariant chain (Ii) (3). Before binding of internalized peptides, Ii is proteolytically removed, leaving a nested set of peptides (termed CLIP, for class II-associated invariant chain peptides) in the peptide-binding cleft of the class II dimer (4, 5). Subsequent removal of CLIP allows binding of the peptides that are eventually presented to the immune system.The process of peptide loading in the MIICs has not been unravelled, but the lysosomal pH value of the MIICs helps to promote peptide loading of class II molecules (6, 7). For instance, low pH increases protease activity, required both for processing of protein antigen (8) and for Ii proteolysis (9). In addition, CLIP removal from class II is facilitated by low pH (10). Finally, pH affects the mechanism of peptide binding itself (11), possibly through protonation of acidic residues involved in peptide complexing in the class II binding cleft (12) or through a conformational change in the class II dimer (13,14). The HLA-DM molecule is another important component for peptide loading. Cell lines mutated for HLA-DM, or transgenic mice lacking the equivalent murine molecule, accumulate class II͞CLIP complexes at the cell surface (15-18). HLA-DM, ...

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Section: Methodsmentioning

confidence: 99%

Interaction between HLA-DM and HLA-DR involves regions that undergo conformational changes at lysosomal pH

Ullrich

Döring

Grüneberg

et al. 1997

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

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“…In these cases, the anisotropy decay is described by an infinite number of exponentially decaying functions. An empirical expression consisting of a limited sum of exponentials and a constant term, the residual anisotropy, r ∞ , has often been used to approximate this decay [11,[45][46][47]:…”

Section: Iv1 Expressions For Time-resolved Polarized Intensities Andmentioning

confidence: 99%

Fluorescence anisotropy measurements in solution: Methods and reference materials (IUPAC Technical Report)

Ameloot

vandeVen

Acuña

et al. 2013

Pure and Applied Chemistry

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After recalling the basic relations relevant to both steady-state and time-resolved fluorescence polarization, it is shown how the values of steady-state polarized intensities recorded experimentally usually need to be corrected for systematic effects and errors, caused by instrumentation and sample properties. A list of selected reference values of steady-state fluorescence anisotropy and polarization is given. Attention is also paid to analysis of time-resolved fluorescence anisotropy data obtained by pulse fluorometry or phase and modulation fluorometry techniques. Recommendations for checking the accuracy of measure ments are provided together with a list of selected time-resolved fluorescence anisotropy data as reported in the literature.

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“…The decay of DPH fluorescence anisotropy reflects the influence of acyl chain packing on DPH motion and orientational order in the hydrophobic core of the membrane (13,14). As shown in Fig.…”

Section: Ay9944 Treatment Causes Alterations In the Physical Propertimentioning

confidence: 94%

“…Measured polarization-dependent differential phases and modulation ratios for each sample were combined with the measured total intensity decay to yield the anisotropy decay, r(t). All anisotropy decay data were analyzed using the Brownian rotational diffusion (BRD) model (14,24) and the results were interpreted in terms of an angular distribution function of DPH, C(u), which is symmetric about u 5 p/2. Relative phospholipid acyl chain packing was quantified using the disorder parameter, C v , which is proportional to the overlap of the DPH orientational probability distribution, C(u)sinu, with randomly oriented DPH (24,25).…”

Section: Membrane Fluidity Measurementsmentioning

confidence: 99%

“…Time-resolved measurements enable discrimination between simultaneous changes in probe lifetime, probe motion, and angular distribution in the membrane hydrophobic core. DPH fluorescence lifetime is exquisitely sensitive to changes in local dielectric properties, making it ideal for assessing changes in transient water penetration into the membrane (13), and time-resolved fluorescence depolarization of DPH can provide detailed information about membrane orientational order and dynamics (13,14).…”

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confidence: 99%

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Alteration of retinal rod outer segment membrane fluidity in a rat model of Smith-Lemli-Opitz syndrome

Boesze‐Battaglia

Damek-Poprawa

Mitchell

et al. 2008

Journal of Lipid Research

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Smith-Lemli-Opitz syndrome (SLOS) is caused by an inherited defect in the last step in cholesterol (Chol) biosynthesis, leading to abnormal accumulation of 7-dehydrocholesterol and decreased Chol levels. Progressive retinal degeneration occurs in an animal model of SLOS, induced by treating rats with AY9944, a selective inhibitor of the enzyme affected in SLOS. Here we evaluated alterations in the biochemical and physical properties of retinal rod outer segment (ROS) membranes in this animal model. At 1 month of AY9944 treatment, there were modest alterations in fatty acid composition, but no significant differences in cis-parinaric acid (cPA) spectroscopic parameters in ROS membranes from treated versus control rats. However, at 3 months, ROS docosahexaenoic acid (DHA) content was dramatically reduced, and cPA fluorescence anisotropy values were decreased, relative to controls. Also, 1,6-diphenyl-1,3,5-hexatriene exhibited decreased rotational motion and increased orientational order in ROS membranes from 3 month-old AY9944-treated rats, relative to controls. No significant changes in protein:lipid ratios were observed; however, rhodopsin regenerability was compromised by 3 months of treatment. These findings are consistent with reduced ROS membrane fluidity in the SLOS rat model, relative to controls, primarily due to the dramatic reduction in membrane DHA levels, rather than altered sterol composition.-Boesze-Battaglia, K., M. Damek-Poprawa, D. C. Mitchell, L. Greeley, R. S. Brush, R. E. Anderson, M. J. Richards, and S. J. Fliesler. Alteration of retinal rod outer segment membrane fluidity in a rat model of Smith-LemliOpitz syndrome.

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Effect of orientational order on the decay of the fluorescence anisotropy in membrane suspensions. A new approximate solution of the rotational diffusion equation

Cited by 128 publications

References 11 publications

Interaction between HLA-DM and HLA-DR involves regions that undergo conformational changes at lysosomal pH

Interaction between HLA-DM and HLA-DR involves regions that undergo conformational changes at lysosomal pH

Fluorescence anisotropy measurements in solution: Methods and reference materials (IUPAC Technical Report)

Alteration of retinal rod outer segment membrane fluidity in a rat model of Smith-Lemli-Opitz syndrome

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