13 research outputs found
Branched peptide with three histidines for the promotion of CuII binding in a wide pH range – complementary potentiometric, spectroscopic and electrochemical studies
Modifications in linear and cyclic peptides have been widely explored in relation with the associated effects
on the coordination of CuII. Branching of peptides is yet another innovative conception to promote metal
binding. The three dimensional (3D), quasi-tripodal structure of the new ligand, H-His-Dap(H-His)-His-NH2
(3H, where Dap = L-2,3-diaminopropionic acid), which is created by the vicinal two N-terminal and one
C-terminal functions of Dap allows triple-arm extension and offers new options in metal binding. A
strategy is presented for the characterization of 3H focusing on the role of structural domains in CuII
binding by comparison of analogous tetrapeptides that involve a varying number of His and Gly residues.
Potentiometric, spectroscopic (UV-Vis, CD and EPR), mass spectrometric and electrochemical data
indicate that in monomeric CuII–3H complexes the metal is bound with higher affinity compared to its
structural domains indicating that the effect of 3D branching should be taken as an important factor for
future studies on CuII peptide constructs
A quantum-chemical study of the binding ability of βXaaHisGlyHis towards copper(II) ion
The present study analyzed binding of Cu2+ to tetrapeptides in water solution at several levels of theoretical approximation. The methods used to study the energetic and structural properties of the complexes in question include semiempirical hamiltonians, density functional theory as well as ab initio approaches including electron correlation effects. In order to shed light on the character of interactions between Cu2+ and peptides, which are expected to be mainly electrostatic in nature, decomposition of interaction energy into physically meaningful components was applied
Extent of metal ion-sulfur binding in complexes of thiouracil nucleosides and nucleotides in aqueous solution
Previously published stability constants of several metal ion (M2+) complexes formed with thiouridines and their 5`-monophosphates, together with recently obtained log K-M(U)(M) versus pK(U)(H) plots for M2+ complexes of uridinate derivatives (U-) allowed now a quantitative evaluation of the effect that the exchange of a (C)O by a (C)S group has on the stability of the corresponding complexes. For example, the stability of the Ni2+, Cu2+ and Cd2+ complexes of 2-thiouridinate is increased by about 1.6, 2.3, and 1.3 log units, respectively, by the indicated exchange of groups. Similar results were obtained for other thiouridinates, including 4-thiouridinate. The structure of these complexes and the types of chelates formed (involving (N3)(-) and (C)S) are discussed. A recently advanced method for the quantification of the chelate effect allows now also an evaluation of several complexes of thiouridinate 5`-monophosphates. In most instances the thiouracilate coordination dominates the systems, allowing only the formation of small amounts of phosphate-bound isomers. Among the complexes studied only the one formed by Cu2+ with 2-thiouridinate 5`-monophosphate leads to significant amounts of the macrochelated isomer, which means that in this case Cu2+ is able to force the nucleotide from the anti to the syn conformation, allowing thus metal ion binding to both potential sites and this results in the formation of about 58 isomer. The remaining 42 coordinated to the thiouracilate residue; Cu2+ binding to the phosphate group occurs in this case only in trace amounts. (c) 2007 Elsevier Inc. All rights reserved
Short-chain oligopeptides with copper(II) binding properties: the impact of specific structural modifications on the copper(II) coordination abilities
A series of linear tetrapeptides containing two histidyl residues in position 2 and 4, namely DHGH, DHGDH, KHGH, KHGdH, Ac-DHGH-NH2, Ac-DHGdH-NH2, Ac-KHGH-NH2, and Ac-KHGdH-NH2, were syn- thesized and characterised. Their copper(II) binding properties were investigated in depth through a vari- ety of physicochemical methods. Potentiometric titrations were first carried out to establish the stoichiometry and the stability of the resulting copper(II)–peptide complexes. The copper(II) chromoph- ores that are formed in the various cases in dependence of pH were subsequently characterised by exten- sive spectroscopic analysis (UV–Vis, EPR, CD) in strict correlation with potentiometric data. The effects of the nature of the first amino acid (Lys versus Asp) and of N-terminal amino group protection on copper(II) binding were specifically addressed. On turn, the careful comparison of the copper(II) coordination abil- ities of the linear peptides with those of their cyclic analogs provided insight into the effects of cyclization on the overall metal binding properties
SOD-Like Activity of Copper(II) Containing Metallopeptides Branched By 2,3-Diaminopropionic Acid: What the N-Termini Elevate, the C-Terminus Ruins
Relations between structural modifiactions and SOD-like activity of four branched CuII-metallopeptides based on L-2,3-diaminopropionic acid are reported. The IC50 values (McCord–Fridovich method) illustrate that enhanced SOD-like activity is warranted by exclusive N-terminal His localization that surmounts the driving force by the CuII/I formal potential
Electrocatalytic water oxidation influenced by the ratio between Cu2+ and a multiply branched peptide ligand
Electrocatalytic water oxidation influenced by the ratio between Cu2+ and a multiply branched peptide ligand
Collin André. Les principaux types morbides des écoliers insuffisants. In: La revue pédagogique, tome 71, Juillet-Décembre 1917. pp. 427-444