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  • BioMed Central  (1)
  • Wiley-Blackwell  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Vibrational assignment of the sn-1 and sn-2 chain carbonyl stretching modes of membrane phospholipids (1982)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 13 (1982), S. 231-234 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Since the carbonyl stretching modes of membrane phospholipids reflect molecular perturbations and reorganizations at the bilayer interface region, a definitive assignment is desired of the vibrations associated with the carbonyl transitions at either the sn-1 or sn-2 lipid chain position. Ether glycerol phospholipids containing one alkyl ether chain and one acyl chain, with the carbonyl group in either the sn-1 or sn-2 chain, provide lipid systems for establishing these assignments. rac-1-0-Hexadecyl-2-palmitoyl-sn -glycero-3-phosphorylcholine yields a carbonyl stretching mode at 1716 cm-1, while the carbonyl mode for 1-palmitoyl-2-0-hexadecyl-sn -glycero-3-phosphorylcholine shifts to 1737 cm-1, By eliminating the gauche bond at the α-carbon position of the sn-2 acyl chain in 1-0-hexadecyl-2-acetoyl-sn-glycero-3-phosphorylcholine, the lower frequency carbonyl fundamental reverts to a higher frequency (1739 cm-1) characteristic of a nearly trans conformation about the C2—C1 bond in the ester linkage.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250130306
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    Paper (German National Licenses)
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    Two-photon time-lapse microscopy of BODIPY-cholesterol reveals anomalous sterol diffusion in chinese hamster ovary cells (2012)
    BioMed Central
    Details
    Publication Date: 2012-10-18
    Description: Background Cholesterol is an important membrane component, but our knowledge about its transport in cells is sparse. Previous imaging studies using dehydroergosterol (DHE), an intrinsically fluorescent sterol from yeast, have established that vesicular and non-vesicular transport modes contribute to sterol trafficking from the plasma membrane. Significant photobleaching, however, limits the possibilities for in-depth analysis of sterol dynamics using DHE. Co-trafficking studies with DHE and the recently introduced fluorescent cholesterol analog BODIPY-cholesterol (BChol) suggested that the latter probe has utility for prolonged live-cell imaging of sterol transport. Results We found that BChol is very photostable under two-photon (2P)-excitation allowing the acquisition of several hundred frames without significant photobleaching. Therefore, long-term tracking and diffusion measurements are possible. Two-photon temporal image correlation spectroscopy (2P-TICS) provided evidence for spatially heterogeneous diffusion constants of BChol varying over two orders of magnitude from the cell interior towards the plasma membrane, where D ~ 1.3 μm2/s. Number and brightness (N&B) analysis together with stochastic simulations suggest that transient partitioning of BChol into convoluted membranes slows local sterol diffusion. We observed sterol endocytosis as well as fusion and fission of sterol-containing endocytic vesicles. The mobility of endocytic vesicles, as studied by particle tracking, is well described by a model for anomalous subdiffusion on short time scales with an anomalous exponent α ~ 0.63 and an anomalous diffusion constant of Dα = 1.95 x 10-3 μm2/sα. On a longer time scale (t 〉 ~5 s), a transition to superdiffusion consistent with slow directed transport with an average velocity of v ~ 6 x 10-3 μm/s was observed. We present an analytical model that bridges the two regimes and fit this model to vesicle trajectories from control cells and cells with disrupted microtubule or actin filaments. Both treatments reduced the anomalous diffusion constant and the velocity by ~40-50%. Conclusions The mobility of sterol-containing vesicles on the short time scale could reflect dynamic rearrangements of the cytoskeleton, while directed transport of sterol vesicles occurs likely along both, microtubules and actin filaments. Spatially varying anomalous diffusion could contribute to fine-tuning and local regulation of intracellular sterol transport.
    Electronic ISSN: 2046-1682
    Topics: Biology , Physics
    Published by BioMed Central
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