Abstract
The polycarboxylate siderophore, rhizoferrin, and its dehydration products were separated by preparative HPLC and characterized by13C-NMR,1H-NMR, UV, circular dichroism (CD) and IR spectroscopy, and also by capillary electrophoresis. Assginment of all carbon atoms and protons by NMR spectra confirmed the structure of rhizoferrin and gave evidence for the presence of the cyclized dehydration byproducts, imidorhizoferrin and bis-imidorhizoferrin. The imido forms were also characterized by their mobility during capillary electrophoresis. UV spectra revealed a 1∶1 iron:ligand ratio above pH 3. Based on the absorption maximum of the metal ligand charge transfer hand at 335 nm a molar extinction coefficient of 2300m −1 cm−1 was calculated for ferric rhizoferrin. CD measurements revealed that the quarternary carbon atoms of the two citric acid residues possess anR,R configuration and that the iron complex of rhizoferrin adopts a A configuration around the metal center.
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Drechsel, H., Jung, G. & Winkelmann, G. Stereochemical characterization of rhizoferrin and identification of its dehydration products. Biometals 5, 141–148 (1992). https://doi.org/10.1007/BF01061320
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DOI: https://doi.org/10.1007/BF01061320