- Comparative study of the reactivity of zirconium(IV)-substituted polyoxometalates towards the hydrolysis of oligopeptides
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The hydrolytic activity of the ZrIV-substituted Keggin-type (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O (1), Lindqvist-type (Me4N)2[W5O18Zr(H2O)3] (2), and Wells-Dawson-type Na14[Zr4(P2W16O59)2(μ3-O)2(OH)2(H2O)4]·57H2O (3) polyoxometalates (POMs) towards the peptide bonds in the oligopeptides triglycine, tetraglycine, glycylglycylhistidine, and glycylserylphenylalanine was investigated by kinetic methods and multinuclear NMR spectroscopy. 31P NMR and UV/Vis spectroscopy showed that 1-3 were stable under the conditions used to study peptide bond hydrolysis. The reactivity of 1-3 towards oligopeptides was compared on the basis of the amount of free glycine produced at a certain time increment. In the presence of 1-3, rate constants in the range 6.25×10-7 to 10.14×10-7 s-1 were obtained, whereas no hydrolysis was observed after one month in the absence of these POMs. The results showed that the Keggin-type complex 1 was the most active towards peptide bond hydrolysis in tri- and tetrapeptides. 1H and 13C NMR spectroscopy showed that triglycine, tetraglycine, and glycylserylphenylalanine interact with 1 and 2 preferentially through the amine nitrogen atom and the N-terminal amide oxygen atom to activate the peptide bond towards hydrolysis. The coordination of glycylglycylhistidine resulted in multiple complexes with 1-3 as a result of additional imidazole coordination to the ZrIV centers.
- Ly, Hong Giang T.,Absillis, Gregory,Parac-Vogt, Tatjana N.
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p. 2206 - 2215
(2015/05/13)
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- Utilizing reversible copper(II) peptide coordination in a sequence-selective luminescent receptor
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Although vast information about the coordination ability of amino acids and peptides to metal ions is available, little use of this has been made in the rational design of selective peptide receptors. We have combined a copper(II) nitrilotriacetato (NTA) complex with an ammonium-ion-sensitive and luminescent benzocrown ether. This compound revealed micromolar affinities and selectivities for glycine- and histidine-containing sequences, which closely resembles those of copper(II) ion peptide binding: the two free coordination sites of the copper(II) NTA complex bind to imidazole and amido nitrogen atoms, replicating the initial coordination steps of non-complexed copper(II) ions. The benzocrown ether recognizes the N-terminal amino moiety intramolecularly, and the significantly increased emission intensity signals the binding event, because only if prior coordination of the peptide has taken place is the intramolecular ammonium ion-benzocrown ether interaction of sufficient strength in water to trigger an emission signal. Intermolecular ammonium ion-benzocrown ether binding is not observed. Isothermal titration calorimetry confirmed the binding constants derived from emission titrations. Thus, as deduced from peptide coordination studies, the combination of a truncated copper(II) coordination sphere and a luminescent benzocrown ether allows for the more rational design of sequence-selective peptide receptors.
- Stadlbauer, Stefan,Riechers, Alexander,Spaeth, Andreas,Koenig, Burkhard
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supporting information; experimental part
p. 2536 - 2541
(2009/04/11)
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- Zinc Complexes of Histidine-Containing Di- and Tripeptides
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Nine dipeptides and one tripeptide containing histidine were converted into analytically pure zinc complexes.Four different compositions were observed.The peptides used as or converted into the monoacids LH (HisGly, GlyHis, HisPhe, HisHis) form the compounds ZnL2 (11a, 12-14) and alternatively (HisGly, HisGlyGly) the compounds ZnL(BF4) (11b, 20).The peptides used as amides (HisGlyNH2, HisMetNH2) act as neutral ligands in the compounds ZnL2(ClO4)2 (15, 16).The three remaining peptides (HisAsp, AlaHis, β-AlaHis) behave like diprotonic acids LH2 forming the compounds ZnL (17-19).Spectra and solubilities indicate that complexes 11a, 13, 15, and 16 are mononuclear containing two chelating peptides bound by their amino and imidazole nitrogen atoms.All other complexes seem to be coordination polymers in some of which the amide N and O atoms are involved in the coordination.This was proven by a structure determination for Zn(GlyHis)2 (12) in which the zinc ions are coordinated octahedrally by two histidine N, two amino N, and two amide O atoms of four peptide residues. - Key Words: Histidine peptides/ Zinc complexes/ Composition/ Solid-state structure
- Foerster, Martin,Vahrenkamp, Heinrich
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p. 541 - 550
(2007/10/02)
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