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Synthesis of tetrahedral copper(II)-thiolate complex as model for the active sites of blue copper proteins
232
Abstracts
MODELLING THE BLUJ3 COPPER SITE WITH IHIDAZOLE-THIOETHER LIGANDS E. Bouwman, W.L. Driessen and J.Reedijk, Gorlaeus Laboratories, Leiden University, P.O.Box 9502, 2300 RA Leiden, THE NETHERLANDS. A direct route to synthesize chelating imidazole-thioether ligands has been developed [l]. The coordination of these ligands with first-row transition metals has been studied extensively. In all compounds the thioether sulfur coordinates to the copper ion, with coordination distances varying between 2.3 and 2.9 A. The coordination geometry of the copper ion is manipulated by variation of the chain length within the ligand, in combination with different choices of the anions. Many different geometries (from compressed octahedral to trigonal bipyramidal) have been encountered. [l] E. Bouwman, W.L. Driessen, Synth. Commun., 18 1581 (1988). Go84
EPR STUDIES OF THE REACTION OF SUBSTRATES WITH COPPER-CONTAINING AMINE OXIDASES. F-y and Yue Zou, Department of Chem istry, Clark University, Worcester, MA 01610, USA. X-band EPR studies of the addition of amine substrates to pig kidney diamine oxidase and bovine plasma amine oxidase under aerobic and anaerobic conditions show that the copper site is affected by the substrates in ways that are enzyme-, substrate-, and time-dependent. In no case is the copper reduced. For diamine oxidase, the substrate p-(N,Ndimethylaminomethyl)benzylamine causes larger changes in the EPR parameters (particularly in g,,) than do putrescine or cadaverine. The changes in the EPR parameters are reversible under aerobic conditions. Results of experiments designed to test whether the communication between the substrate and the copper(I1) are direct or conformationally-transmitted will be described.
GO85
6086
SYNTHESIS OF TETRAHEDRAL COPPER(THIOLATE COMPLEX AS MODEL FOR THE ACTIVE SITES OF BLUE COPPER PROTEINS. N. Kitajima, K. Fujisawa, and Y. R~oro-oka,Research Laboratory of Resources Utilization,Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku,
Yokohama
227, Japan.
The reaction of t-BUSH with a u-hyrdoxo binuclear copper(I1) complex, [Cu(HB(3,5-iPr PZ)~)]~(OH)~ in CH2C12, yielding the formation of a mononuclear copper t II)-thlolate complex, Cu(t-BuS)(HB(3,5-iPr2pz)3) (HB(3,5-iPr2pz)3=hydrotris(3,5-diisopropyl-l-pyra~olyl)borate), which can closely mimic the characteristic spectroscopic properties of blue copper proteins; a strong S+Cu LMCT band at 607 nm (E, ca. 3000) and an axial symmetric EPR signal with the parameters, g&=2.21, g1=2.07, A,,= 70 G, although the redox potential (-0.35 V vs. SCE) is considerably lower than those of blue copper proteins.
Abstracts
MODELLING THE BLUJ3 COPPER SITE WITH IHIDAZOLE-THIOETHER LIGANDS E. Bouwman, W.L. Driessen and J.Reedijk, Gorlaeus Laboratories, Leiden University, P.O.Box 9502, 2300 RA Leiden, THE NETHERLANDS. A direct route to synthesize chelating imidazole-thioether ligands has been developed [l]. The coordination of these ligands with first-row transition metals has been studied extensively. In all compounds the thioether sulfur coordinates to the copper ion, with coordination distances varying between 2.3 and 2.9 A. The coordination geometry of the copper ion is manipulated by variation of the chain length within the ligand, in combination with different choices of the anions. Many different geometries (from compressed octahedral to trigonal bipyramidal) have been encountered. [l] E. Bouwman, W.L. Driessen, Synth. Commun., 18 1581 (1988). Go84
EPR STUDIES OF THE REACTION OF SUBSTRATES WITH COPPER-CONTAINING AMINE OXIDASES. F-y and Yue Zou, Department of Chem istry, Clark University, Worcester, MA 01610, USA. X-band EPR studies of the addition of amine substrates to pig kidney diamine oxidase and bovine plasma amine oxidase under aerobic and anaerobic conditions show that the copper site is affected by the substrates in ways that are enzyme-, substrate-, and time-dependent. In no case is the copper reduced. For diamine oxidase, the substrate p-(N,Ndimethylaminomethyl)benzylamine causes larger changes in the EPR parameters (particularly in g,,) than do putrescine or cadaverine. The changes in the EPR parameters are reversible under aerobic conditions. Results of experiments designed to test whether the communication between the substrate and the copper(I1) are direct or conformationally-transmitted will be described.
GO85
6086
SYNTHESIS OF TETRAHEDRAL COPPER(THIOLATE COMPLEX AS MODEL FOR THE ACTIVE SITES OF BLUE COPPER PROTEINS. N. Kitajima, K. Fujisawa, and Y. R~oro-oka,Research Laboratory of Resources Utilization,Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku,
Yokohama
227, Japan.
The reaction of t-BUSH with a u-hyrdoxo binuclear copper(I1) complex, [Cu(HB(3,5-iPr PZ)~)]~(OH)~ in CH2C12, yielding the formation of a mononuclear copper t II)-thlolate complex, Cu(t-BuS)(HB(3,5-iPr2pz)3) (HB(3,5-iPr2pz)3=hydrotris(3,5-diisopropyl-l-pyra~olyl)borate), which can closely mimic the characteristic spectroscopic properties of blue copper proteins; a strong S+Cu LMCT band at 607 nm (E, ca. 3000) and an axial symmetric EPR signal with the parameters, g&=2.21, g1=2.07, A,,= 70 G, although the redox potential (-0.35 V vs. SCE) is considerably lower than those of blue copper proteins.