Spectroscopic studies of the charge transfer and vibrational features of binuclear copper(II) azide complexes: comparison to the coupled binuclear copper active site in met azide hemocyanin and tyrosinase

Pate, James E.; Ross, Paul K.; Thamann, Thomas J.; Reed, Christopher A.; Karlin, Kenneth D.; Sorrell, Thomas N.; Solomon, Edward I.

doi:10.1021/ja00196a029

Cited by 107 publications

(74 citation statements)

References 2 publications

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“…Thus, it is proposed that binding of azide to the phenol-bound form of AO occurs according to Scheme 1. Azide binds to type 3 copper in the terminal mode, since the spectral features of the azide-Cu-(II) LMCT band lack the multicomponent structure characteristic of bridging azide (Pate et al, 1989;Casella et al, 1993), particularly in the CD spectra, where the low-energy component of the LMCT band, between 450 and 500 nm, which is weaker in absorption, becomes dominant (Beltramini et al, 1995). Both azide molecules are supposed to bind to the same (upper) type 3 copper atom of the couple, since this is the one accessible from the solvent.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

et al. 1997

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Competitive inhibition by phenolic compounds of the ascorbic acid oxidation reaction catalyzed by ascorbate oxidase was investigated at pH 7.0 and 23.0 degrees C. Inhibition of p-nitrophenol is pH dependent over the range 5.0-8.0, with inhibitor binding favored at higher pH. Bulky substituents on the phenol nucleus reduce or prevent the inhibitory effect. The presence of phenol affects the binding characteristics of azide to the trinuclear cluster of the enzyme. In particular, binding of azide to type 2 copper is prevented, and the affinity of azide to type 3 copper is reduced. In addition, reduction of type 1 copper is observed upon prolonged incubation of ascorbate oxidase with excess phenol and azide, but not with phenol alone. It is proposed that binding of phenolic inhibitors occurs at or near the site where the substrate (ascorbate) binds. NMR relaxation measurements of the protons of phenols in the presence of ascorbate oxidase show paramagnetic effects due to the proximity of the bound inhibitor to a copper center, likely type 1 copper. Copper-proton distance estimates between this paramagnetic center and p-cresol or p-nitrophenol bound to ascorbate oxidase are between 4.4 and 5.9 A.

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Section: Discussionmentioning

confidence: 99%

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

et al. 1997

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“…This change results in the blue color developed by type 3 copper proteins upon oxygenation. The active sites of phenoloxidase and hemocyanins with oxygen bound to the copper atoms exhibit similar spectroscopic properties with respect to UV-resonance Raman, X-ray absorption and UV/VIS spectroscopy (Eickman et al, 1978;Himmelwright et al, 1980;Pate et al, 1989;Della Longa et al, 1993;Karlin, 1993;Solomon et al, 1994Solomon et al, , 1996Spritz et al, 1997;Itoh et al, 2001;Metz and Solomon, 2001):…”

Section: Active Sitementioning

confidence: 99%

Similar enzyme activation and catalysis in hemocyanins and tyrosinases

Decker

Schweikardt

Nillius

et al. 2007

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137

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“…The symmetric shape of the LMCT optical bands indicates that azide binds in the terminal mode to the copper(II) centers in all cases, [9] while bridging azide gives rise to characteristic multicomponent LMCT bands. [10,11] The sizeable intensity of the azido-Cu II LMCT band indicates that it is electric dipole allowed; this implies that there must be good overlap between the donor, π(N 3 -), and acceptor, d x 2 -y 2, orbitals, [11] and therefore that azide binds in the Cu equatorial plane. In addition, as observed systematically for copper(II)-azido complexes, [9,[10][11][12] azide binding is accompanied by an increase in the absorption of the LF bands.…”

Section: Characterization Of the Azido Adducts Of Copper-phi Complexesmentioning

confidence: 99%

Ligand Binding, Conformational and Spectroscopic Properties, and Biomimetic Monooxygenase Activity by the Trinuclear Copper–PHI Complex Derived from L‐Histidine

et al. 2008

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The trinuclear copper(II) complex derived from the octadentate N‐donor ligand PHI [piperazine‐1,4‐bis(4‐{N‐[1‐acetoxy‐3‐(1‐methyl‐1H‐imidazol‐4‐yl)]‐2‐propyl}‐N‐(1‐methyl‐1H‐imidazol‐2‐ylmethyl)aminobutyl)] contains two equivalent CuA centers bound by tridentate arms and a CuB center bound by a central didentate residue. The conformational and ligand binding properties of the complex were extensively studied by various spectroscopic techniques (UV/Vis, CD, NMR, EPR) to probe its behavior in solution. Studies on the binding properties of the complex performed with the azide anion as a probe showed that the ligand preferably binds to the CuA centers of the complex and only weakly to the CuB center. The EPR spectra showed the existence of a strong coupling between one of the two CuA centers and the CuB center, which appears to be mediated by a hydroxido‐bridging ligand. Further information about metal binding was obtained by analyzing the NMR spectra of the trinuclear ZnII3–PHI complex, which serves as an analogue of the extremely oxygen sensitive CuI3–PHI complex. The latter complex does not form a stable dioxygen adduct at low temperature, but exhibits an interesting monooxygenase activity. This was studied at low temperature using p‐chlorophenolate as a substrate; the formation of 4‐chlorocatechol in sizeable yield indicates that some of the very reactive CunO2 intermediate should be involved.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Spectroscopic studies of the charge transfer and vibrational features of binuclear copper(II) azide complexes: comparison to the coupled binuclear copper active site in met azide hemocyanin and tyrosinase

Cited by 107 publications

References 2 publications

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Similar enzyme activation and catalysis in hemocyanins and tyrosinases

Ligand Binding, Conformational and Spectroscopic Properties, and Biomimetic Monooxygenase Activity by the Trinuclear Copper–PHI Complex Derived from L‐Histidine

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