Tristhiolato Pseudopeptides Bind Arsenic(III) in an AsS3 Coordination Environment Imitating Metalloid Binding Sites in Proteins

The AsIII binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand L1 ) or d-penicillamine residues (ligand L2 ) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of...

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Bibliographic Details
Published in:Inorganic chemistry 2023-05, Vol.62 (17), p.6817-6824
Main Authors: Szekeres, Levente I., Maldivi, Pascale, Lebrun, Colette, Gateau, Christelle, Mesterházy, Edit, Delangle, Pascale, Jancsó, Attila
Format: Article
Language:English
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Summary:The AsIII binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand L1 ) or d-penicillamine residues (ligand L2 ) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of the experimental data, obtained with the variation of the AsIII:ligand concentration ratios or pH values in some instances, evidence the exclusive formation of species with an AsS3-type coordination mode. The UV-monitored titration of the ligands with arsenous acid at pH = 7.0 provided an absorbance data set that allowed for the determination of apparent stability constants of the forming species. The obtained stabilities (logK′ = 5.26 (AsL1 ) and logK′ = 3.04 (AsL2 )) reflect high affinities, especially for the sterically less restricted cysteine derivative. DFT calculated structures correlate well with the spectroscopic results and, in line with the 1H NMR data, indicate a preference for the all-endo conformers resembling the AsIII environment at the semimetal binding sites in various metalloproteins.
ISSN:0020-1669
1520-510X
DOI:10.1021/acs.inorgchem.3c00563