An electronic structural comparison of copper-peroxide complexes of relevance to hemocyanin and tyrosinase active sites

Ross, Paul K.; Solomon, Edward I.

doi:10.1021/ja00009a005

Cited by 166 publications

(136 citation statements)

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“…In addition, the cupric ions must be strongly antiferromagnetically coupled by the bound peroxide, since oxygenated hemocyanins are EPR silent (Dooley et al, 1978). Based on these data several models for the oxygenated dinuclear copper site in hemocyanin have been proposed (Eickman et al, 1979;Maddaluno & Giessner-Prettre, 1991;Ross & Solomon, 1991).…”

Section: B Hazes Et Almentioning

confidence: 99%

Crystal structure of deoxygenated limulus polyphemus subunit II hemocyanin at 2.18 Å resolution: Clues for a mechanism for allosteric regulation

et al. 1993

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The crystal structure of Limulus polyphemus subunit type I1 hemocyanin in the deoxygenated state has been determined to a resolution of 2.18 A . Phase information for this first structure of a cheliceratan hemocyanin was obtained by molecular replacement using the crustacean hemocyanin structure of Panulirus interruptus. The most striking observation in the Limulus structure is the unexpectedly large distance of 4.6 A between both copper ions in the oxygen-binding site. Each copper has approximate trigonal planar coordination by three histidine NE atoms. No bridging ligand between the copper ions could be detected. Other important new discoveries are (1) the presence of a cis-peptide bond between Glu 309 and Ser 310, with the carbonyl oxygen of the peptide plane hydrogen bonded to the N6 atom of the copper B ligand His 324; (2) localization of a chloride-binding site in the interface between the first and second domain; (3) localization of a putative calcium-binding site in the third domain. Furthermore, comparison of Limulus versus Panulirus hemocyanin revealed considerable tertiary and quaternary rigid body movements, although the overall folds are similar. Within the subunit, the first domain is rotated by about 7.5" with respect to the other two domains, whereas within the hexamer the major movement is a 3.1 O rotation of the trimers with respect to each other. The rigid body rotation of the first domain suggests a structural mechanism for the allosteric regulation by chloride ions and probably causes the cooperative transition of the hexamer between low and high oxygen affinity states. In this postulated mechanism, the fully conserved Phe 49 is the key residue that couples conformational changes of the dinuclear copper site into movements of the first domain.

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Section: B Hazes Et Almentioning

confidence: 99%

Crystal structure of deoxygenated limulus polyphemus subunit II hemocyanin at 2.18 Å resolution: Clues for a mechanism for allosteric regulation

et al. 1993

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“…Due to their capabilities, like molecular oxygen transport (hemocyanin) or oxidation (tyrosinase), they have been subject to many theoretical [1][2][3][4][5][6][7][8] and experimental [9][10] investigations. Theoretically, their complicated electronic structures are particularly interesting due to the possibility of an antiferromagnetic coupling related to the open-shell singlet nature of the central metallic core.…”

Section: Introductionmentioning

confidence: 99%

Comments on the nature of the bonding in oxygenated dinuclear copper enzyme models

Piquemal

Pilmé

2006

Journal of Molecular Structure: THEOCHEM

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“…This methodology has been successfully used to describe transitionmetal systems, including a large number of magnetically coupled centers in metalloproteins. 23,171216 The broken-symmetry approach can correctly model the antiferromagnetic states in magnetically coupled systems, and consequently it is accepted as a good representation of the nonorthogonal, natural magnetic orbitals in dinuclear complexes. Taking the cognizance of its limitation, we used the broken-symmetry method to elucidate essential electronic features and reactions of the diiron complexes of MMOH.…”

mentioning

confidence: 99%

Quantum Chemical Studies on Dioxygen Activation and Methane Hydroxylation by Diiron and Dicopper Species as well as Related Metal–Oxo Species

Yoshizawa

2013

Bulletin of the Chemical Society of Japan

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Quantum chemical studies by the author and co-workers on dioxygen activation and methane hydroxylation by diiron and dicopper enzyme species as well as related metaloxo species are reviewed. The activation of the OO bond of dioxygen at the mono-and dimetal sites of metalloenzymes is an essential process in the initial catalytic stages of naturally occurring oxygenation reactions. A way of orbital thinking about dioxygen activation at diiron and dicopper enzymes is developed at the extended Hückel level of theory. Two different reaction pathways that lead from dimetal peroxo complexes with¯-η , and CuO + are systematically analyzed on the basis of density functional theory (DFT) calculations. An important feature in the reaction is the spin crossover between the highspin and low-spin potential energy surfaces in particular in the CH activation process. The spin inversion from the highspin state to the low-spin state effectively decreases the barrier height of CH activation. Another feature in the reaction is that no radical species is involved in the course of the hydroxylation because the methyl species formed as a result of the CH bond cleavage can directly coordinate to the metal active site. The coupling of the OH and CH 3 ligands occurs to produce methanol at the metal active center. The reaction profiles obtained from DFT calculations are similar to those of the Gif chemistry proposed by D. H. R. Barton, in particular the involvement of the HOMCH 3 species as an intermediate in the hydroxylation of methane. The nonradical mechanism is extended to methane hydroxylation by the diiron and dicopper species of methane monooxygenase (MMO). This mechanism is possible when the metal active center is coordinatively unsaturated to have a space for the coordination of the OH and CH 3 groups as ligands. Although compelling discussion to support the involvement of oxygen-and carbon-centered radicals is provided, the nonradical mechanism still seems to be applicable for methane hydroxylation from the viewpoint of reaction selectivity. Kinetic isotope effects (KIEs) in the CH activation process by the bare FeO + complex and diiron and dicopper enzyme models are compared with respect to the radical and nonradical mechanisms by using transition state theory.

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An electronic structural comparison of copper-peroxide complexes of relevance to hemocyanin and tyrosinase active sites

Cited by 166 publications

References 1 publication

Crystal structure of deoxygenated limulus polyphemus subunit II hemocyanin at 2.18 Å resolution: Clues for a mechanism for allosteric regulation

Crystal structure of deoxygenated limulus polyphemus subunit II hemocyanin at 2.18 Å resolution: Clues for a mechanism for allosteric regulation

Comments on the nature of the bonding in oxygenated dinuclear copper enzyme models

Quantum Chemical Studies on Dioxygen Activation and Methane Hydroxylation by Diiron and Dicopper Species as well as Related Metal–Oxo Species

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