Article Dans Une Revue Biomacromolecules Année : 2025

Binding of Fe 2+ to Polygalacturonate: Structure of Dimers and Coordination Geometry

Résumé

We performed enhanced sampling molecular dynamics simulations to check to what extent the egg-box model (EBM) describes the binding of Fe2+ to alpha-D-(1 -> 4) polygalacturonic acid (polyGalA). In agreement with the EBM, two octameric polyGalA chains in the presence of four Fe2+ cations (R total = [Fe2+]/[GalA] = 0.25) formed dimers mostly composed of 4 GalA-Fe2+-GalA cross-links (R bound approximate to 0.25), and Fe2+ cations were preferentially bound to polyGalA chains in a monodentate coordination mode, owing to their tight interaction with their hydration water. Yet, at variance with the EBM, dimers with irregular cross-link patterns and/or with a missing cross-link were also sampled to significant amounts, and the hydroxyl oxygen atoms from GalA units did not participate significantly to the first coordination shell of Fe2+. Therefore, this study suggests that the EBM does not capture the details of the local structures of Fe2+-cross-linked polyGalA dimers and of the first coordination shell of bound Fe2+ cations, as previously observed for Ca2+.

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Dates et versions

hal-05110556 , version 1 (13-06-2025)

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Adrien Lerbret, Ali Assifaoui. Binding of Fe 2+ to Polygalacturonate: Structure of Dimers and Coordination Geometry. Biomacromolecules, 2025, ⟨10.1021/acs.biomac.5c00120⟩. ⟨hal-05110556⟩
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