Synthesis, structure and catalase-like activity of a new dinuclear mixed valence MnIIMnIII complex containing an unsymmetric N5O2 donor ligand

Karsten, P.; Neves, Ademir; Bortoluzzi, Adaı́lton J.; Strähle, Joachim; Maichle-Mössmer, C.

doi:10.1016/s1387-7003(02)00435-5

Cited by 50 publications

(75 citation statements)

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“…Previously, catalase activity toward H 2 O 2 for [Mn(II)Mn(III)(L1)(OAc) 2 ] þ was reported. 15 Here, the hydrolytic activity of the complex was assessed using 2,4-bis(dinitrophenyl)phosphate (BDNPP) as the substrate (Figure 2). The activity maximizes at ∼pH g 10, and fitting the data to eq 1, derived for a monoprotic system, yields a pK a of 8.2.…”

Section: X-raymentioning

confidence: 99%

“…On the basis of mechanistic schemes discussed for other isostructural complexes 15,22,86,90,91,113,114 and several enzymatic systems (e.g., PAPs 18,19 ) the following reaction mechanism for the Mn(II)Mn(III) complex is proposed. At low pH (<8) the likely nucleophile involved in hydrolysis is a terminally Mn(III) bound hydroxide (Scheme 2), with the substrate bound only to the divalent metal ion.…”

Section: Articlementioning

confidence: 99%

“…The complex shows significant catalase activity, with a k cat =2.48 ( 0.15 s -1 and a K M = 83 ( 1 mM and has been previously characterized by structural determination and electrochemistry. 15 Electrochemical measurements have indicated that the heterovalent oxidation state is stabilized by the asymmetry of the ligand, similar to the isostructural Fe(II)Fe(III) complex. 16 The latter is a biomimetic model for PAPs, especially the animal enzymes, which require heterovalent diiron centers for catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Catalytic Characterization of a Heterovalent Mn(II)Mn(III) Complex That Mimics Purple Acid Phosphatases

Smith¹,

Riley²,

Noble

et al. 2009

Inorg. Chem.

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The binuclear heterovalent manganese model complex [Mn(II)Mn(III)(L1)(OAc) 2 ] ClO 4 3 H 2 O (H 2 L1 = 2-(((3-((bis-(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino)-methyl)phenol) has been prepared and studied structurally, spectroscopically, and computationally. The magnetic and electronic properties of the complex have been related to its structure. The complex is weakly antiferromagnetically coupled (J ∼ -5 cm -1 , H = -2J S 1 3 S 2 ) and the electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectra identify the Jahn-Teller distortion of the Mn(III) center as predominantly a tetragonal compression, with a significant rhombic component. Electronic structure calculations using density functional theory have confirmed the conclusions derived from the experimental investigations. In contrast to isostructural M(II)Fe(III) complexes (M = Fe, Mn, Zn, Ni), the Mn(II)Mn(III) system is bifunctional possessing both catalase and hydrolase activities, and only one catalytically relevant pK a (= 8.2) is detected. Mechanistic implications are discussed.

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Section: X-raymentioning

confidence: 99%

Section: Articlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Catalytic Characterization of a Heterovalent Mn(II)Mn(III) Complex That Mimics Purple Acid Phosphatases

Smith¹,

Riley²,

Noble

et al. 2009

Inorg. Chem.

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“…2) and the complex [FeNi (bpbpmp)(l-OAc) 2 ](ClO 4 ) (1) were prepared as described previously [29][30][31]. …”

Section: Preparation Of Biomimetic Complexesmentioning

confidence: 99%

“…Biomimetics provide an additional method to probe the role of a metal ion in a catalytic cycle. A series of isostructural Fe(III)M(II) complexes (M is Fe, Mn, Cu, Zn) that mimic the coordination environment of PAPs, and that have the characteristic purple/pink color, have recently been described [24][25][26][27][28][29][30][31]. Of particular interest is the observation that at least in the Fe(III)Zn(II) complex, the best characterized of these mimics, only the terminal, Fe(III)-bound hydroxide is sufficiently strong a nucleophile to induce catalysis [28].…”

Section: Introductionmentioning

confidence: 99%

Probing the role of the divalent metal ion in uteroferrin using metal ion replacement and a comparison to isostructural biomimetics

et al. 2007

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Purple acid phosphatases (PAPs) are a group of heterovalent binuclear metalloenzymes that catalyze the hydrolysis of phosphomonoesters at acidic to neutral pH. While the metal ions are essential for catalysis, their precise roles are not fully understood. Here, the Fe(III)Ni(II) derivative of pig PAP (uteroferrin) was generated and its properties were compared with those of the native Fe(III)Fe(II) enzyme. The k cat of the Fe(III)Ni(II) derivative (approximately 60 s -1 ) is approximately 20% of that of native uteroferrin, and the Ni(II) uptake is considerably faster than the reconstitution of full enzymatic activity, suggesting a slow conformational change is required to attain optimal reactivity. An analysis of the pH dependence of the catalytic properties of Fe(III)Ni(II) uteroferrin indicates that the l-hydroxide is the likely nucleophile. Thus, the Ni(II) derivative employs a mechanism similar to that proposed for the Ga(III)Zn(II) derivative of uteroferrin, but different from that of the native enzyme, which uses a terminal Fe(III)-bound nucleophile to initiate catalysis. Binuclear Fe(III)Ni(II) biomimetics with coordination environments similar to the coordination environment of uteroferrin were generated to provide both experimental benchmarks (structural and spectroscopic) and further insight into the catalytic mechanism of hydrolysis. The data are consistent with a reaction mechanism employing an Fe(III)-bound terminal hydroxide as a nucleophile, similar to that proposed for native uteroferrin and various related isostructural biomimetics. Thus, only in the uteroferrin-catalyzed reaction are the precise details of the catalytic mechanism sensitive to the metal ion composition, illustrating the significance of the dynamic ligand environment in the protein active site for the optimization of the catalytic efficiency.

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Redox Chemistry of a Dimanganese(II,III) Complex with an Unsymmetric Ligand: Water Binding, Deprotonation and Accumulative Light‐Induced Oxidation

et al. 2006

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Synthesis, structure and catalase-like activity of a new dinuclear mixed valence MnIIMnIII complex containing an unsymmetric N5O2 donor ligand

Cited by 50 publications

References 12 publications

Structural and Catalytic Characterization of a Heterovalent Mn(II)Mn(III) Complex That Mimics Purple Acid Phosphatases

Structural and Catalytic Characterization of a Heterovalent Mn(II)Mn(III) Complex That Mimics Purple Acid Phosphatases

Probing the role of the divalent metal ion in uteroferrin using metal ion replacement and a comparison to isostructural biomimetics

Redox Chemistry of a Dimanganese(II,III) Complex with an Unsymmetric Ligand: Water Binding, Deprotonation and Accumulative Light‐Induced Oxidation

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