Agarose structure

R. Takano, K. Hayashi, S. Hara, and S. Hirase, Funoran from the red seaweed, Gloiopeltis compla-nata Polysaccharides with sulphated agarose structure and their precursor structure, Carbohydr. Polym., 27 (1995) 305-311. 

Figure 1.10 also confirms the agarose structure of the extracted material after the alkali treatment. The structures of both the raw and alkali-treated agar show significant changes in their peaks. 

The family of agarose-based gels, Sepharose, Sepharose CL, and Sepharose Fast Flow, are bead-formed gels prepared from 2, 4, or 6% agarose solutions. The matrix porosity decreases and rigidity of the bead structure increases with increasing agarose concentrations. The open pore structure and broad... 

Small-angle X-ray scattering (SAXS), circular dichroism (CD), and UV spectroscopy at different temperatures were used to investigate the nature of calf-thymus DNA in aqueous solution, in the presence of [Me Sn] " (n = 1-3) species. The results demonstrate that the [MeSn(IV)] moiety does not influence the structure and conformation of the DNA double helix, and does not degrade DNA, as indicated by agarose gel electrophoresis. Inter alia, the radii of gyration, Rg, of the cross section of native calf-thymus DNA, determined by SAXS in aqueous solution in the presence of [Me Sn] " (n = 1-3) species are constant and independent of the nature and concentration of the [Me Sn] species. 

FIG. 4 Chemical composition and physical structure of agarose gels. (Reprinted by permission of Wiley-VCH and P. Serwerfrom Ref. 350, Copyright 1983, WUey-VCH.)... 

The structure of these gel-like systems of micelles is very different from that of conventional electrophoresis media made from chemically and physically cross-linked polymers of polyacrylamide and agarose [75], The absence of chemical or physical cross-links in the Pluronic gel-like phases may allow a larger degree of freedom for macromolecular transport around the obstacles that make up the medium than occurs in conventional electrophoresis media. 

Key, PY Sellen DB, A Laser Light-Scattering Study of the Structure of Agarose Gels, Journal of Polymer Science 20, 659, 1982. 

Maaloum, M Pernodet, N Tinland, B, Agarose Gel Structure Using Atomic Force Microscopy Gel Concentration and Ionic Strength Effects, Electrophoresis 19, 1606, 1998. Mackie, IS Meares, P, The Diffusion of Electrolytes in a Cation-Exchange Resin Membrane I. Theortical, Proceedings of the Royal Society of London Series A 232, 498, 1955. 

P. Aymard, D.R. Martin, K. Plucknett, TJ. Foster, A.H. Clark, and I.T. Norton, Influence of thermal history on the structural and mechanical properties of agarose gels. Biopolymers 59,131—144 (2001). 

Agarose and its O-methyl, sulfate, 0-(2-hydroxyethyl), and 0-(car-boxyethylidene) derivatives give diffraction diagrams corresponding to a common molecular structure. A double helix having an axial periodicity of 9.5 A (950 pm) was proposed. Each chain in the double helix is a left-handed, threefold helix of pitch 19.0 A (1.90 nm), and it is translated axially, relative to its partner, by 9.5 A (950 pm). 

In actual practice, the inert gels of dextran (I)-a polyglucose or other types of polymers, for instance agarose and polyacrylamides, wherein the macromolecules invariably are cross-linked to afford a reasonably porous 3D-structure, served as the stationary phases in size-exclusion chromatography. 

Ion-exchange resins are cross-linked polymers which are typically polystyrene, cellulose or agarose based. Polystyrene is hydrophobic in nature and useful for inorganic ions and small molecules while cellulose and agarose are hydrophilic and more useful for the larger, biologically important molecules, e.g. proteins and nucleic acids, which either would be adversely affected by a hydrophobic environment or could not gain access to the small pore structure. 

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