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001-es BibID:BIBFORM010536
Első szerző:Rajković, Snežana
Cím:A study of the reactions of a methionine- and histidine-containing tetrapeptide with different Pd(II) and Pt(II) complexes: selective cleavage of the amide bond by platination of the peptide and steric modification of the catalyst / Snežana Rajković, Marija D. Živković, Csilla Kállay, Imre Sóvágó, Miloš I. Djuran
Dátum:2009
ISSN:1477-9226
Megjegyzések:H-1 NMR spectroscopy was applied to the study of the reactions of [M(en)(H2O)(2)](2+) complexes (M = Pd(II) and Pt(II)) with the N-acetylated methionyl-glycyl-histidyl-glycineamide, MeCOMet-Gly-His-GlyNH(2). All reactions were performed in the pH range 1.5-2.0 with equimolar amounts of the [M(en)(H2O)(2)](2+) complex and the tetrapeptide at 60 degrees C. In all these reactions, a metal(II) complex bound to a methionine residue affects the regioselective cleavage of the amide bond involving the carboxylic group of methionine. The priority in the cleavage of the Met-Gly amide bond in relation to the other amide bonds in this peptide is due to the high affinity of Pt( II) and Pd( II) ions for the sulfur donor atom. The mechanism of these hydrolytic reactions is discussed and, for its clarification, the reaction of the [Pd(en)(H2O)(2)](2+) complex with MeCOMet-Gly-His-GlyNH(2) was additionally investigated by potentiometric titration. The steric effects of the various palladium( II) complexes of the type [Pd(L)(H2O)(2)](2+), in which L is a chelating diamine (ethylenediamine, en, 2-picolylamine, pic, or 2,2-dipyridylamine, dpa) on the hydrolytic cleavage of the amide bond involving the carboxylic group of histidine in the MeCOMet-Gly-His-GlyNH(2) tetrapeptide were also studied by H-1 NMR spectroscopy. All reactions were performed under the above-mentioned conditions and in the initial stage of these reactions, the MeCOMet-Gly-His-GlyNH(2) was reacted with an equimolar amount of the [Pt(dien)Cl](+) complex (dien is diethylenetriamine) and then the monoplatinated [Pt(dien)(MeCOMet-Gly-His-GlyNH(2)-S)](2+) complex was treated with an equimolar amount of [Pd(L)(H2O)(2)](2+). It was found that the rate of hydrolysis of the His-GlyNH(2) amide bond in [Pt(dien)(MeCOMet-Gly-His-GlyNH(2)-S)](2+) decreased from the en to the pic complex, with finally a total inhibition of this reaction with [Pd(dpa)(H2O)(2)](2+). These results are an important step in the study of the regioselective cleavage of peptides and proteins and in the development of new palladium( II) complexes as artificial metallopeptidases.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Dalton Transactions. - (2009), p. 8370-8377. -
További szerzők:Živković, Marija D. Kállay Csilla (1978-) (vegyész) Sóvágó Imre (1946-) (vegyész) Djuran, Miloš I.
Internet cím:DOI
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001-es BibID:BIBFORM006215
Első szerző:Rajković, Snežana
Cím:Complex formation processes of terminally protected peptides containing two or three histidyl residues. Characterization of the mixed metal complexes of peptides / Snežana Rajković, Csilla Kállay, Richárd Serényi, Gerasimos Malandrinos, Nick Hadjiliadis, Daniele Sanna and Imre Sóvágó
Dátum:2008
Megjegyzések:Copper(II), nickel(II) and zinc(II) complexes of the peptides Ac-HVVH-NH2 and Ac-HAAHVVH-NH2 have been studied by potentiometric, UV-vis, CD, EPR and NMR spectroscopic measurements. Both tetra and heptapeptides can form relatively stable macrochelates with copper(II), nickel(II) and zinc(II) ions, in which the ligands are coordinated via the side-chain imidazole functions. Formation of the macrochelates slightly suppresses, but cannot prevent the copper(II) and nickel(II) ion promoted deprotonation and coordination of the amide functionalities. The overall stoichiometry of the major species is [MH-3L](-) with a 4N (=N-, N-, N-, N-im) coordination mode. In the case of Ac-HAAHVVH-NH2, coordination isomers of this species can exist with a preference for copper(II) or nickel(II) binding at the internal histidyl residue. In the copper(II)-Ac-HAAHVVH-NH2 system, the presence of the two anchoring sites results in the formation of dinuclear complexes. The existence of these species requires the involvement of amide functions in metal binding. Both equilibrium and spectroscopic data support the fact that the copper(II) ions of the dinuclear species are independent from each other providing a good chance for the formation of various mixed metal complexes. It was found that zinc(II) is not able to significantly alter the copper(II) binding of the heptapeptide, but it can occupy the uncoordinated histidyl sites. The formation of the copper(II) - nickel(II) mixed species was obtained in alkaline solutions and CD spectra suggest the statistical distribution of the two metal ions among the histidyl residues. The binding of HAAHVVH to palladium(II) is exclusive below pH 8 and the mixed metal species of palladium(II) and copper(II) ions are formed only in slightly basic solutions.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Dalton Transactions. - 37 (2008), p. 5059-5071. -
További szerzők:Kállay Csilla (1978-) (vegyész) Serényi Richárd Malandrinos, Gerasimos Hadjiliadis, Nick Sanna, Daniele (1956-) (vegyész) Sóvágó Imre (1946-) (vegyész)
Internet cím:elektronikus változat
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