Agarose fibers

In an agarose gel (the usual choice), the obstacles provided by the agarose fibers can be expected to lead to a molecular size-dependent electrophoretic mobility i(K), This method has been used for more than two decades to separate nucleic acids of various sizes. However, it soon became evident that this approach was limited for instance, it was observed experimentally that large nucleic acids (>50 kbp) possess a molecular size-independent mobility even in a dense gel moreover, the mobility was observed to be strongly field-dependent. 

Likewise, these forces may generate inhomogeneous distributions of DMA inside the tube, especially in areas of the gel where the agarose fibers are closer to each other (smaller pores). Finally, it should be noted that since the forces / = < E u- (see Eq. (10)) acting on the primitive segments unit vectors u. can point in all... 

The supports employed for covalent attachment of enzymes can be classified into two groups a) natural (agarose, dextran, cellulose, porous glass, silica, the optical fiber itself or alumina) and b) synthetic (acrylamide-... 

Analyses of the reeonstituted eomplexes by quantitative agarose gel electrophoresis [404,405] and analytical ultracentrifugation [266,406] in the presence of MgCl2 showed that the arrays were able to fold in a way that is almost indistinguishable from complexes reconstituted with major histones (see Fig. 14A-B). Despite this, it was found that histone H2A ubiquitination affects the MgCl2 solubility of the reconstituted complexes (see Fig. 14C) suggesting that this modification may play a role in enhancing the intermolecular associations between chromatin fibers [221]. 

The structures of agarose, iota- and kappa-carrageenan have been determined by x-ray fiber diffraction (24-27). The quality of the diffraction data obtained from each of these three specimens varies considerably and the way in which these data are used in structure determination is outlined here. Diffraction patterns from oriented specimens of agarose, and kappa- and iota-carrageenan are shown in Figure 6 (28). The molecular repeat distances derived from these patterns are listed in Table I. 

Figure 6. X-ray fiber diffraction patterns from (a) agarose, (b) Ca " iota-carrageenan, and (c) K " kappa-carrageenan. (Reproduced with permission from ref. 28. Copyright 1989 Elsevier.)...

Seaweed [FOOD ADDITIVES] (Vol 11) agarose from [ELECTROSEPARATIONS - ELECTROPHORESIS] (Vol 9) gums from [GUMS] (Vol 12) mineral nutrients source [MINERAL NUTRIENTS] (Vol 16) plant growth regulators fiom [GROWTH REGULATIONS - PLANT] (Vol 12) source ofdietary fiber [DIETARY FIBER] (Vol 8)... 

Carrier properties. Carriers can be shaped and configured as films, fibers, planar surfaces, or spheres. Surface morphology, i.e., surface texture and porosity, can exert a decisive influence as can carrier materials the most important are inorganic materials such as ceramics or glass, synthetic polymers such as nylon or polystyrene, and polysaccharide materials such as cellulose, agarose, or dextran. 

Natural supports (agarose, dextran, cellulose, porous glass, silica, the optical fiber itself or alumina) and synthetic resins (acrylamide-based polymers, methacrylic acid-based polymers, maleic anhydride-based polymers, styrene-based polymers or nylon, to name a few) have been applied for covalent attachment of enzymes. These materials must display a high biocatalyst binding capacity (as the linearity and the limit of detection of the sensing layers will be influenced by this value), good mechanical and chemical stability, low cost, and ease of preparation. 

Another type of behavior is obtained with thermoreversible gels like agarose. Electron microscopy has shown that the network structure of these gels consists of fibers made from many polymer chains. In such gels, elasticity doesn t come from the entropy of the chains, as in the case of covalently cross-linked polymers, but from the mechanical bending elasticity of the fibers. The elastic moduli are about 10 times larger than those of entropic... 

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