Effect of the types and arrangements of donor atoms on Pb(II) versus Zn(II) binding preference of selected amino acids, peptides and derivatives

•The order of the Pb(II)-binding ability of the investigated donors is S ≫ O ∼ N.•Both the type and arrangement of the donor atoms affect the Pb(II)-binding.•N-donors prefer Zn(II) over Pb(II).•Zn(II) and Pb(II) binding abilities of O-donor are similar to each other.•Perfect selectivity of Pb(II) over Zn(II) with dipeptide containing side chain S-donors in adequate position is achieved.

Pb(II) complexes in solution formed with different amino acids [glycine (Gly), aspartic acid (Asp), histidine (His), methionine (Met), S-methyl-cysteine (SMC) and penicillamine (Pen)], dipeptides (GlyGly, GlyVal (Val = valine), GlyMet, MetGly, GlyHis, HisGly, GlyAsp, AspGly, CysGly (Cys = cysteine), AlaCys, GlyGlu (Glu = glutamic acid), GluVal, SerGly (Ser = serine)), tripeptides (GlyGlyGly, GlyMetGly, GlyGlyMet, MetMetMet), as well as two peptidehydroxamic acids [(alanyl-alanine hydroxamic acid (AlaAlaNHOH) and N-methyl-alanyl-alanine hydroxamic acid AlaAlaN(CH3)OH)] have been studied by pH-potentiometry, 1H NMR and ESI-MS measurements. The effects of the types and arrangements of the donor atoms on the Pb(II)-binding ability as well as on the selectivity for Pb(II) over Zn(II) were evaluated. Out of the investigated molecules, the Pb(II) binding ability of Pen is far the best, but compared to this ligand, somewhat better selectivity for Pb(II) over Zn(II) can be achieved with S-containing dipeptides.

Graphical abstractPb(II) complexes in solution formed with numerous amino acids, dipeptides, tripeptides, as well as with two peptidehydroxamic acids have been studied by pH-potentiometry, 1H NMR and ESI-MS measurements. The best Pb(II) binding ability was found with Pen (penicillamine), but compared to this ligand, somewhat better selectivity for Pb(II) over Zn(II) with S-containing dipeptide, AlaCys was obtained.Figure optionsDownload full-size imageDownload as PowerPoint slide