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09:31
Calcium Carbonate Formation in the Presence of Biopolymeric Additives
Published on: May 14, 2019
Molecular basis of calcium binding by polyguluronate chains. Revising the egg-box model
1Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 9, Krakow 30-239, Poland. wojtek_plazinski@o2.pl
Journal of Computational Chemistry
|October 7, 2011
Summary
This study reveals a new model for calcium-polyguluronate interactions, challenging the classic egg-box structure. Calcium ions coordinate with polyguluronate chains and water molecules, explaining polyuronate association in solutions.
Area of Science:
- Biochemistry
- Materials Science
- Computational Chemistry
Background:
- The egg-box model is the established structure for calcium alginate/guluronate.
- This model posits calcium ions binding in chelation sites between polyuronate chains.
Purpose of the Study:
- To investigate the interactions between calcium and polyuronates.
- To understand the mechanism of Ca(2+)-induced polyuronate chain association in aqueous solutions.
Main Methods:
- Molecular dynamics simulations.
- Semiempirical (ZINDO-1/Monte Carlo) calculations.
Main Results:
- Proposed new structural models for Ca(2+)-polyguluronate complexes (parallel and antiparallel pairing).
- Found Ca(2+) ions coordinated by four carboxyl oxygens from two polyguluronate chains and four water molecules.
- Observed competition between water and polyguluronate for calcium ion coordination.
Conclusions:
- The findings challenge the classical egg-box model for calcium alginate/guluronate structure.
- The proposed coordination pattern aligns with experimental data and the "shifted" egg-box model.
- Competition for calcium ions influences the structural arrangement of polyuronate complexes.
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