Glyphosate and ATP binding by mononuclear Zn(ii) complexes with non-symmetric ditopic polyamine ligands

Abstract

Binding of Zn(II) by the ditopic ligands L1py, L2py and L1para, composed of a cyclam unit linked to the linear polyamines 1,4,8,11-tetraazaundecane (L1py and L2para) and 1,4,7-triazaheptane (L2py) via a 2,6-dimethylpyridinyl (L1py and L2py) or a 1,4-dimethylbenzyl spacer (L2para), has been analyzed by means of potentiometric and (1)H and (13)C NMR measurements. All ligands form stable mononuclear Zn(II) complexes in a wide pH range, featuring the metal ion bound to the macrocyclic unit. The open-chain polyamine unit can easily bind several protons in aqueous solution affording protonated metal complexes at neutral and acidic pH values. These complexes behave as bifunctional receptors for the anionic substrates N-(phosphonomethyl)glycine (glyphosate or PMG) and ATP. Potentiometric, (1)H and (31)P NMR measurements show that the Zn(II) complex with L1py is the better receptor for both substrates, thanks to the simultaneous presence of a pyridine linker functionalized at its 2,6 positions and of a flexible linear tetraamine chain. In fact, these structural features allow a stronger interaction of PMG and ATP with both the protonated tetraamine moiety and the Zn(II)-cyclam core.

Inhibition Mechanisms of Zn Precipitation on Aluminum Oxide by Glyphosate: A 31P NMR and Zn EXAFS Study

“…Because of the similar atomic number of N and O, EXAFS cannot distinguish between these two elements as backscattering atoms. However, according to previous structural studies on metal/glyphosate complexation ,, and Zn/organic ligand complexation, we presumed the presence of direct bonding between Zn and N in the first shell. For the second shell, we can satisfactorily fit it with 1 C atom at 2.90 Å, suggesting that Zn complexed with the carboxyl group of glyphosate.…”

Library Synthesis, Screening, and Discovery of Modified Zinc(II)-Bis(dipicolylamine) Probe for Enhanced Molecular Imaging of Cell Death

“…There are four sets of scaffolds: mono-DPA scaffolds with one or two appended 2-amido substituents (compounds 6 and 10 ) and bis-DPA scaffolds with two or four appended 2-amido substituents (compounds 7 and 11 ). The focus on 2-amido substituents was intentional because literature precedence suggested that the NH residues were likely to form attractive hydrogen bonds to the proximal oxyanion residues within the headgroup of a bound PS (Scheme ). − …”

“…As shown in Scheme 1, the primary coordination bonding with the two zinc cations is strengthened by additional secondary noncovalent interactions with the PS headgroup such as electrostatic attraction, hydrogen bonding, and hydrophobic insertion into the membrane. 33,34 The molecular design concept of modified scaffolds has been used before to enhance binding affinity of Zn-BDPA structures to small, water-soluble phosphorylated target molecules such as inorganic phosphate, 35−38 nucleoside polyphosphates, 39 and phosphorylated peptides. 40−42 However, there is no reported attempt to improve Zn-BDPA recognition of PS buried in a bilayer membrane.…”

“…Here, we describe an alternative but complementary design strategy that employs a single Zn-BDPA core scaffold, and attempts to enhance PS recognition by appending relatively small functional groups. As shown in Scheme , the primary coordination bonding with the two zinc cations is strengthened by additional secondary noncovalent interactions with the PS headgroup such as electrostatic attraction, hydrogen bonding, and hydrophobic insertion into the membrane. , The molecular design concept of modified scaffolds has been used before to enhance binding affinity of Zn-BDPA structures to small, water-soluble phosphorylated target molecules such as inorganic phosphate, − nucleoside polyphosphates, and phosphorylated peptides. − However, there is no reported attempt to improve Zn-BDPA recognition of PS buried in a bilayer membrane. The strategy of designing modified Zn-BDPA scaffolds de novo using computer modeling was judged to be unreliable given the structural flexibility of the Zn-BDPA scaffold and the dynamic, amphiphilic properties of a target PS-rich bilayer membrane.…”

Recognition of AMP, ADP and ATP through Cooperative Binding by Cu(II) and Zn(II) Complexes Containing Urea and/or Phenylboronic—Acid Moieties

“…[ 23 , 24 , 25 , 26 , 27 ] The formation of macrochelates was clearly defined for adenine nucleotides, thanks to the coordination of both the phosphate chains and the nitrogen N-7 of the purine residue. [ 28 , 29 ] Since then, different types of molecular receptors have been used for the recognition of phosphorylated anions in aqueous media [ 1 ]: (1) Linear or macrocyclic positively charged receptors, generally polyammonium systems [ 30 , 31 , 32 , 33 ] or receptors containing guanidinium or imidazolium groups [ 34 , 35 ]; (2) Metal complexes, generally coordinatively unsaturated Cu 2+ or Zn 2+ complexes, with acyclic (i.e., dipicolyl or terpyridyl derivatives [ 36 , 37 , 38 , 39 , 40 , 41 , 42 ] or Schiff base ligands [ 43 ]) or macrocyclic ligands [ 44 , 45 , 46 ]; (3) Ditopic receptors that combine a metal coordinating unit and hydrogen-bond donors to reinforce anion binding [ 47 , 48 ].…”