Stewart, Matthew B.; Gray, Stephen R.; Vasiljevic, Todor; Orbell, John D.
Exploring the molecular basis for the metal-mediated assembly of alginate gels
CARBOHYDRATE POLYMERS, 102:246-253, FEB 15 2014

The binding of sodium and calcium ions to single and multiple poly-G decamer strands has been modelled by conducting a series of molecular dynamics simulations. Implications for metal mediated inter-strand interactions and gel assembly have been explored by systematically introducing up to three strands into each of these simulations. A particular emphasis has been placed on revealing intrinsic binding modes by an unbiased initial positioning of the metal ions. The results have revealed binding modes that provide a rationale for the observed gelling of alginate by calcium rather than sodium ions. A number of junction zones involving calcium ions have been identified that result in chain aggregation. This includes a distinctive perpendicular motif that appears to be ubiquitous in previously reported AFM images of open 3-D alginate networks. The coordination geometries of the metal ions have been characterised and the metal-mediated junctions between associated strands are described in detail. (C) 2013 Elsevier Ltd. All rights reserved.

DOI:10.1016/j.carbpol.2013.11.034

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