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Structure, Equilibrium and Ribonuclease Activity of Copper(II) and Zinc(II) Complexes Formed with a Dinucleating Bis-Imidazole Ligand

2000; Wiley; Volume: 2000; Issue: 7 Linguagem: Inglês

10.1002/1099-0682(200007)2000

1099-0682

Tamás Gajda, Roland Krämer, Attila Jancsó,

Synthesis and Characterization of Heterocyclic Compounds

European Journal of Inorganic ChemistryVolume 2000, Issue 7 p. 1635-1644 Full Paper Structure, Equilibrium and Ribonuclease Activity of Copper(II) and Zinc(II) Complexes Formed with a Dinucleating Bis-Imidazole Ligand Tamás Gajda, Tamás Gajda tamas.gajda@chem.u-szeged.hu Department of Inorganic and Analytical Chemistry, University of Szeged 6701 Szeged, P.O. Box 440, Hungary, Fax: (internat.) +36/62-420-505Search for more papers by this authorRoland Krämer, Roland Krämer Anorganisch-Chemisches Institut der Universität, Wilhelm-Klemm Straße 8, 48149 Münster, GermanySearch for more papers by this authorAttila Jancsó, Attila Jancsó Department of Inorganic and Analytical Chemistry, University of Szeged 6701 Szeged, P.O. Box 440, Hungary, Fax: (internat.) +36/62-420-505Search for more papers by this author Tamás Gajda, Tamás Gajda tamas.gajda@chem.u-szeged.hu Department of Inorganic and Analytical Chemistry, University of Szeged 6701 Szeged, P.O. Box 440, Hungary, Fax: (internat.) +36/62-420-505Search for more papers by this authorRoland Krämer, Roland Krämer Anorganisch-Chemisches Institut der Universität, Wilhelm-Klemm Straße 8, 48149 Münster, GermanySearch for more papers by this authorAttila Jancsó, Attila Jancsó Department of Inorganic and Analytical Chemistry, University of Szeged 6701 Szeged, P.O. Box 440, Hungary, Fax: (internat.) +36/62-420-505Search for more papers by this author First published: July 2000 https://doi.org/10.1002/1099-0682(200007)2000:7 3.0.CO;2-JCitations: 49AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract The syntheses, crystal structures, solution equilibria and ribonuclease activity are reported for copper(II) and zinc(II) complexes of a new potentially dinucleating, bis-imidazole ligand N,N′-bis(5-methylimidazol-4-ylmethyl)-1,3-diaminopropan-2-ol (bimido). The zinc(II) ion in [Zn(bimido)Cl]NO3 is coordinated in a slightly distorted square pyramidal environment, with the four N atoms of bimido in the basal positions and the Cl− ion in the axial one. The two copper(II) ions in [Cu2(bimido−1H)(DPP)(ClO4)(CH3OH)]ClO4·1/2 H2O (DPP = diphenyl phosphate) are bridged by the deprotonated alkoxo group of bimido and by the phosphate group of DPP in a 1,3-bridging mode. Depending on the [M]/[L] ratio, the ML and M2L−2H species are present in solution in the neutral pH range, having analogous structures as described above for the crystalline complexes. The zinc(II)-bimido (2/1) system, in a 65% EtOH-H2O mixed solvent, shows an important increase of hydrolytic activity, parallel with the formation of the Zn2L−2H species, with a sigmoidal pH-rate profile modelling both steps of RNA hydrolysis. The kcat value for the transesterification of 2-hydroxypropyl-p-nitrophenyl phosphate by Zn2L−2H, determined from saturation kinetic measurements (T = 298 K), corresponds to a maximum rate acceleration (kcat/kuncat) of ca. 104. The observed pseudo-first order rate constant for the hydrolysis of uridine 2′,3′-cyclic monophosphate, under nearly physiological conditions (T = 310 K, pH = 8, [Zn2L−2H] = 3.6 mM, kobs = 2·10−5 s−1) reflects a higher hydrolytic activity of Zn2L−2H towards this biologically relevant substrate (kobs/kuncat indicates ca. 104 fold rate acceleration). The proposed mechanisms include bifunctional Lewis-acid and general base catalysis. Citing Literature Volume2000, Issue7July 2000Pages 1635-1644 RelatedInformation