Lipid analogs fluorescent

Macro domains of micrometer size have been reported when using an ordinary microscope. The typical procedure is to use 2% of a fluorescent lipid analog, which renders visible a domain pattern. This, of course, assumes that the fluorescence moiety has no effect on the assembly structure. There is (generally) no information about the thickness of the domains. The shapes of domains are varied, and very complex (circular or near-circular domains, parallel stripes, or more irregular, wormlike, or similar kinds of structures). 

Fig. 9. (Top) NSOM fluorescence image of a DPPC bilayer in which the bottom monolayer contains the fluorescent lipid analog diICl8. (Bottom) NSOM force image of the same bilayer. Reproduced with permission from Ref. [18]. Copyright 1998 The Biophysical Society.

Fig. 2. General structural features of fluorescent and spin-labeled lipid analogs. The fluorescent lipids usually contain a short-chain fatty acid, amino-caproic acid, that is derivatized with 4-nitrobenzo-2-oxa-1,3-diazole (NBD), or valeric acid that is derivatized with a boron dipyrromethene difluoride (BODIPY) moiety. For fluorescent phospholipids, X can be hydrogen or the esterified forms of choline, ethanolamine, serine, or inositol. R>r fluorescent sphingolipids, Y can be hydrogen or the esterified fonns of phosphocholine or mono- or oligosaccharides typical of glycosphingolipids. The spin-labeled lipids modified in the fatty acid portion contain a 4-doxylpentanoyl fatty acid in the sn-2 position. Those modified in the polar head group contain a tempocholine moiety in place of choline. The X substituent for the acyl spin-labeled lipids can be hydrogen or the esterified forms of choline, ethanolamine, or serine.

Bromobimane was also used for preparation of a fluorescent lipid analog which is suitable for use in lipid bilayers <8582203 >. 

Naylor, B. L. Picardo, M. Homan, R. Pownall, H. J. Effects of fluorophore structure andhydrophobicity on the uptake and metabolism of fluorescent lipid analogs. Chetn. Phys. Lipids 1991,58,111-119. 

By means of this method, a variety of Ras proteins with different lipidation patterns could be synthesized in multimilligram amounts. For instance, proteins were generated with the natural lipid combination, i.e. a farnesyl thioether and a palmitoyl thioester. Furthermore, analogous proteins were synthesized embodying only one lipid residue in which either the farnesyl- or the palmitoyl group was replaced by a stable hexadecyl thioether. In addition, proteins were built up containing a serine instead of a cysteine residue at the critical sites which normally are lipidated. In a further series of experiments, lipidated Ras proteins which carry a fluorescent Mant group incorporated into the farnesyl-type modification were synthesized.1251... 

During the fusion process the relative surface area decreases with increasing volume indicating a loss of membrane material (about 22% in Fig. 51). In analogy to the fusion process of protoplasts it can be assumed that the excess lipid is removed in form of small, submicroscopic vesicles (Fig. 52). The electric breakdown in the membrane contact zone leads to the formation of several pores in which lipid molecules are randomly oriented (Fig. 52 b). The molecules reorient forming submicroscopic vesicles and the new membrane of the fused vesicle (Fig. 52c). Thus, fused giant liposomes should contain small, submicroscopic vesicles. This could possibly be proven by using fluorescence-labelled lipids for liposome fusion. 

Use of fluorescent sphingolipid analogs to study lipid transport along the endocytic pathway. Methods 2005 36 186-195. 57. 

In vitro and in vivo studies have shown that short-chain cer-amides induce growth arrest (154). A fluorescent analog of C6-ceramide partitioned into caveolin-enriched microdomains of rat aorta vascular smooth muscle cells and led to growth arrest via activation of PKC-zeta, which is recruited to lipid microdomains and subsequently reduces the activity of Akt (155). 

Fluorescence micrograph of hamster intestinal epithelium after cellular uptake into lipid droplets of an orally administered fluorescent analog of cholesterol (fluoresterol, dissolved in corn oil) from the intestinal lumen (upper left, unstained). [C. P. Sparrow et al., 1999, J. Lipid Res. 40 1747-1757.]... 

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