Recent Structural Work on the Oxygen Transport Protein Hemocyanin

Magnus, Karen A.; Ton-That, H.; Carpenter, Joan E.

doi:10.1021/cr00027a009

Cited by 381 publications

(246 citation statements)

References 31 publications

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“…Copper proteins with a type-3 site, like hemocyanin and the enzymes tyrosinase and catechol oxidase are important dioxygenprocessing proteins [2][3][4][5][6]. These metallo-enzymes, which use molecular oxygen from air as the primary oxidant, are generally considered as very sophisticated catalysts.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of dimethanol-bis(1,3-bis(3,5-dimethylpyrazol-1-yl)- propan-2-olato)dicopper(II) dibromide, [Cu2(C13H19N4O)2(CH3OH)2]Br2

Zhang

Dou

She

et al. 2006

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialA solution of 0.2 g (0.8 mmol) of 1,3-bis(3,5-dimethylpyrazol-1-yl)propan-2-ol (Hdpzhp) [1] in 20 ml of methanol was treated with 32 mg (0.8 mmol) of NaOH and stirred further for 30 min at room temperature. This ligand solution was combined with a solution of 0.178 g (0.8 mmol) of CuBr 2 in 20 ml of methanol and stirred further for 1 h. The resulting dark blue solution was filtered and allowed to stand at RT. Large dark blue single crystals suitable for X-ray diffraction were formed after a few days. Elemental Analysis: found C, 39.79 %; H, 5.12 %; N, 13.58 %; calc. for C 28H46Br2Cu2N8O4 C, 39.77 %; H, 5.48 %; N, 13.25 %. DiscussionCopper proteins with a type-3 site, like hemocyanin and the enzymes tyrosinase and catechol oxidase are important dioxygenprocessing proteins [2][3][4][5][6]. These metallo-enzymes, which use molecular oxygen from air as the primary oxidant, are generally considered as very sophisticated catalysts. Their reactions are very fast and highly efficient while operating under mild conditions with high substrate specificity, regio-selectivity and yield, and having mostly water as the only ¢waste¢ product [7]. The title crystal structure consists of a [Cu 2(MeOH)2(dpzhp)2] 2+ cation and two Br anions. The cation is a dinuclear copper complex coordinated by two methanol molecules and two molecules of ligand bridged to each other by means of two alkoxo oxygen atoms. The Cu1Cu1A distance is 3.030(2) Å, which agrees well with the corresponding distances of 2.990. Each copper ion is coordinated by two nitrogen atoms and two oxygen atoms of two ligands in a distorted square-planar environment. The average terminal CuN(pyrazole) distance (1.961 Å) is comparable to that reported [1] and the average bridging CuO(alcoholic hydroxy) bond distance (1.925 Å) is similar to those of reported complexes. In this complex, the N1Cu1N3 and Cu1O1O1¢ angles are 102.3(2)°and 76.2(2)°. The axial Cu1Br1 and Cu1O2(methanol) distances are 3.948(2) Å and 2.757(7) Å, respectively. The oxygen atoms of the methanol groups contact the Br atoms through OH···Br hydrogen bonds (3.214(6) Å) in a molecular layer.

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Section: Discussionmentioning

confidence: 99%

Crystal structure of dimethanol-bis(1,3-bis(3,5-dimethylpyrazol-1-yl)- propan-2-olato)dicopper(II) dibromide, [Cu2(C13H19N4O)2(CH3OH)2]Br2

Zhang

Dou

She

et al. 2006

Zeitschrift Für Kristallographie - New Crystal Structures

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“…Their contribution to the structure factors was secured by back-Fourier transformation (program PLATON [32]CALC SQUEEZE, 303 e ( unit cell (1 ). For all structures a selection of the crystal data and additional parameters are presented in Table 2.…”

Section: X-ray Structure Determinationsmentioning

confidence: 99%

Dinuclear copper(II) complexes of four new pyrazole-containing macrocyclic ligands are active catalysts in the oxidative coupling of 2,6-dimethylphenol

Schuitema

Aubel

Koval

et al. 2003

Inorganica Chimica Acta

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Four new macrocyclic ligands of varying ring size, [22] (D), show the pyrazole groups and the amine nitrogens all to be involved in the coordination of the copper(II) ions. In the mononuclear compound A the copper ion is in a distorted octahedral geometry, with the equatorial plane formed by four nitrogen donor atoms from the ligand and the axial positions occupied by two oxygen atoms from mono-coordinated perchlorate anions. In compound B each copper ion is in a distorted square pyramidal environment, with the three ligand nitrogens and a chloride atom in the equatorial plane and another chloride atom in the axial position. The cation of compound C contains four copper centers. Two bridging Cl atoms connect the two central copper atoms to form a centrosymmetric four membered ring. Two macrocyclic units are present in the cation, each containing two copper atoms bridged by a chloride atom. One copper is fivefold coordinated and the second copper is distorted octahedral. In compound D both copper(II) ions are in a distorted octahedral N 5 O environment, with the equatorial plane formed by the three ligand nitrogens and a nitrogen from an acetonitrile molecule. A second acetonitrile molecule and a mono-coordinated perchlorate anion are weakly bound in the axial positions. The copper nitrate compounds of these new ligands are to some degree active catalysts in the oxidative coupling of 2,6-dimethylphenol with molecular dioxygen to poly(2,6-dimethyl-1,4-phenylene ether). #

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“…These systems either have mononuclear or multinuclear copper centers, but in this work we will focus on systems with a binuclear copper center only. Examples of binuclear copper containing enzymes are, for instance, hemocyanin, tyrosinase, and catechol oxidase [20][21][22][23]. Thus, tyrosinase enzymes and their biomimetics bind molecular oxygen on a dicopper center to form a l-g that oxidizes phenols to catechol [20,24,25].…”

Section: Introductionmentioning

confidence: 99%

“…Examples of binuclear copper containing enzymes are, for instance, hemocyanin, tyrosinase, and catechol oxidase [20][21][22][23]. Thus, tyrosinase enzymes and their biomimetics bind molecular oxygen on a dicopper center to form a l-g that oxidizes phenols to catechol [20,24,25]. Aromatic hydroxylation as performed by tyrosinase enzymes is a challenging process and difficult to achieve due to the strength of the C-H bond.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory studies of oxygen and carbonate binding to a dicopper patellamide complex

Latifi

Bagherzadeh

Milne

et al. 2008

Journal of Inorganic Biochemistry

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a b s t r a c tIn this work we present results of density functional theory (DFT) calculations on dicopper patellamides and their affinity for molecular oxygen and carbonate. Patellamides are cyclic octapeptides that are produced by a cyanobacterium, and may show promise as therapeutics. Thus, carbonate binding to a dicopper patellamide center gives a stable cyclic octapeptide with a twist of almost 90°. The system exists in closelying open-shell singlet and triplet spin states with two unpaired electrons in orthogonal r Ã orbitals on each metal center. Subsequently, we replaced carbonate with dioxygen and found a stable Cu 2 (l-O) 2 diamond shaped patellamide core. In this structure the original dioxygen bond is significantly weakened to essentially a single bond, which should enable the system to transfer these oxygen atoms to substrates. We predicted the IR and Raman spectra of the Cu 2 (l-O) 2 diamond shaped patellamide structure using density functional theory and found a considerable isotope effect on the O-O stretch vibration for 16 O 2 versus 18 O 2 bound structures. Our studies reveal that carbonate forms an extremely stable complex with dicopper patellamide, but that additional molecular oxygen to this system does not give a potential oxidant. Therefore, it is more likely that carbonate prepares the system for dioxygen binding by folding it into the correct configuration followed in the proposed catalytic cycle by a protonation event preceding dioxygen binding to enable the system to reorganize to form a stable Cu 2 (l-O) 2 -patellamide cluster. Alternatively, carbonate may act as an inhibitor that blocks the catalytic activity of the system. It is anticipated that the Cu 2 (l-O) 2 -patellamide structure is a potential active oxidant of the dicopper patellamide complex.Crown

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Recent Structural Work on the Oxygen Transport Protein Hemocyanin

Cited by 381 publications

References 31 publications

Crystal structure of dimethanol-bis(1,3-bis(3,5-dimethylpyrazol-1-yl)- propan-2-olato)dicopper(II) dibromide, [Cu2(C13H19N4O)2(CH3OH)2]Br2

Crystal structure of dimethanol-bis(1,3-bis(3,5-dimethylpyrazol-1-yl)- propan-2-olato)dicopper(II) dibromide, [Cu2(C13H19N4O)2(CH3OH)2]Br2

Dinuclear copper(II) complexes of four new pyrazole-containing macrocyclic ligands are active catalysts in the oxidative coupling of 2,6-dimethylphenol

Density functional theory studies of oxygen and carbonate binding to a dicopper patellamide complex

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