Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Feb;20(2):255-263.
doi: 10.1007/s43630-021-00014-0. Epub 2021 Feb 11.

Fe(III)-polyuronic acid photochemistry: radical chemistry in natural polysaccharide

M H Jayan S Karunarathna  1 , Mayokun J Ayodele  1 , Giuseppe E Giammanco  1 , Alexander M Brugh  1 , Dayana A Muizzi  1 , Mariia A Bauman  1 , Andrew T Torelli  1   2 , Anginelle M Alabanza  3 , Malcolm D E Forbes  4   5 , Alexis D Ostrowski  6
Affiliations

Fe(III)-polyuronic acid photochemistry: radical chemistry in natural polysaccharide

M H Jayan S Karunarathna et al. Photochem Photobiol Sci. 2021 Feb.

Abstract

The photochemistry of Fe(III) coordinated to natural uronate-containing polysaccharides has been investigated quantitatively in aqueous solution. It is demonstrated that the photoreduction of the coordinated Fe(III) to Fe(II) and oxidative decarboxylation occurs in a variety of uronate-containing polysaccharides. The photochemistry of the Fe(III)-polyuronic acid system generated a radical species during the reaction which was studied using the spin trapping technique. The identity of the radical species from this reaction was confirmed as CO2•- indicating that both bond cleavage of the carboxylate and oxidative decarboxylation after ligand to metal charge transfer radical reactions may be taking place upon irradiation. Degradation of the polyuronic acid chain was investigated with dynamic light scattering, showing a decrease in the hydrodynamic radius of the polymer assemblies in solution after light irradiation that correlates with the Fe(II) generation. A decrease in viscosity of Fe(IIII)-alginate after light irradiation was also observed. Additionally, the photochemical reaction was investigated in plant root tissue (parsnip) demonstrating that Fe(III) coordination in these natural materials leads to photoreactivity that degrades the pectin component. These results highlight that this Fe(III)-polyuronic acid can occur in many natural systems and may play a role in biogeochemical cycling of iron and ferrous iron generation in plants with significant polyuronic acid content.

Keywords: Biogeochemical iron cycling; Bioinorganic photochemistry; Carbon radicals; Iron photochemistry; Polysaccharides.

PubMed Disclaimer

References

    1. Amin, A. S., Green, H. D., Küpper, C. F., & Carrano, J. C. (2009). Vibrioferrin, an unusual marine siderophore: iron binding, photochemistry, and biological implications. Inorganic Chemistry, 48(23), 11451–11458. - DOI
    1. Barbeau, K., Rue, E. L., Bruland, K. W., & Butler, A. (2001). Photochemical cycling of iron in the surface ocean mediated by microbial iron(iii)-binding ligands. Nature, 413(6854), 409–413. - DOI
    1. Butler, A., & Theisen, R. M. (2010). Iron(III)-siderophore coordination chemistry: Reactivity of marine siderophores. Coordination Chemistry Reviews, 254(3–4), 288–296. - DOI
    1. Hardy, C. D., & Butler, A. (2018). β-Hydroxyaspartic acid in siderophores: biosynthesis and reactivity. Journal of Biological Inorganic Chemistry, 23(7), 957–967. - DOI
    1. Miller, E. P., Böttger, L. H., Weerasinghe, A. J., Crumbliss, A. L., Matzanke, B. F., Meyer-Klaucke, W., et al. (2014). Surface-bound iron: a metal ion buffer in the marine brown alga Ectocarpus siliculosus? Journal of Experimental Botany, 65(2), 585–594. - DOI

LinkOut - more resources