Proton-coupled electron transfer in Fe-superoxide dismutase and Mn-superoxide dismutase

Miller, Anne‐Frances; Padmakumar, K.; Sorkin, David L.; Карапетян, А. В.; Vance, Carrie K.

doi:10.1016/s0162-0134(02)00621-9

Cited by 78 publications

(89 citation statements)

References 61 publications

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Section: Mn-containing Biological Systemsmentioning

confidence: 99%

“…Many Mn-dependent enzymes take advantage o f the rich redox chemistry available to the metal, accessing the +2, +3, +4, and perhaps even the +5 oxidation states during their turnover. For example, Mn-superoxide dismutase (MnSOD), which detoxifies the cell of the superoxide radical , cycles between the Mn(II) and Mn(III) oxidation states via the ping-pong type mechanism shown below [5][6][7][8][9].(1a) (1b) Other examples of such mononuclear redox-active enzymes include the manganese peroxidase responsible for lignin degradation by white-rot fungus [10][11][12]; a unique Mndependent form of lipoxygenase [13][14][15][16]; oxalate decarboxylase [17,18]; as well as an extradiol catechol dioxygenase [19][20][21]. …”

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confidence: 99%

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Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

et al. 2007

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Electron paramagnetic resonance studies at multiple frequencies (MF EPR) can provide detailed electronic structure descriptions of unpaired electrons in organic radicals, inorganic complexes, and metalloenzymes. Analysis of these properties aids in the assignment of the chemical environment surrounding the paramagnet and provides mechanistic insight into the chemical reactions in which these systems take part. Herein, we present results from pulsed EPR studies performed at three different frequencies (9, 31, and 130 GHz) on [Mn(II)(H 2 O) 6 ] 2+ , Mn(II) adducts with the nucleotides ATP and GMP, and the Mn(II)-bound form of the hammerhead ribozyme (MnHH). Through line shape analysis and interpretation of the zero-field splitting values derived from successful simulations of the corresponding continuous-wave and field-swept echodetected spectra, these data are used to exemplify the ability of the MF EPR approach in distinguishing the nature of the first ligand sphere. A survey of recent results from pulsed EPR, as well as pulsed electron-nuclear double resonance and electron spin echo envelope modulation spectroscopic studies applied to Mn(II)-dependent systems, is also presented. Mn-Containing Biological SystemsManganese operates as a cofactor in numerous proteins, serving both catalytic and structural roles [1][2][3][4]. Many Mn-dependent enzymes take advantage o f the rich redox chemistry available to the metal, accessing the +2, +3, +4, and perhaps even the +5 oxidation states during their turnover. For example, Mn-superoxide dismutase (MnSOD), which detoxifies the cell of the superoxide radical , cycles between the Mn(II) and Mn(III) oxidation states via the ping-pong type mechanism shown below [5][6][7][8][9].(1a) (1b) Other examples of such mononuclear redox-active enzymes include the manganese peroxidase responsible for lignin degradation by white-rot fungus [10][11][12]; a unique Mndependent form of lipoxygenase [13][14][15][16]; oxalate decarboxylase [17,18]; as well as an extradiol catechol dioxygenase [19][20][21]. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptIn order to help minimize kinetic and thermodynamic penalties associated with electron transfer events and the execution of chemical reactions, two or more metal centers can be coupled together to provide active sites capable of conducting multiple electrons while still operating within a physiologically accessible range of reduction potentials [22]. Only three such examples of redox-active polynuclear Mn enzymes are known: Mn-catalase that disproportionates hydrogen peroxide [23][24][25][26]; a Mn form of ribonucleotide reductase (Mn-RNR) [27,28]; and, arguably the most recognized Mn-dependent enzyme, the photosynthetic core of green plants, algae, and certain cyanobacteria termed photosystem II (PSII) [29,30]. Through a series of photoinitiated electron transfer events, oxidizing equivalents are stored on the tetranuclear Mn core of PSII -the oxygen-evolving complex (OEC) -which then extracts four electr...

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Section: Mn-containing Biological Systemsmentioning

confidence: 99%

mentioning

confidence: 99%

Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

et al. 2007

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“…Thus, the favorable first half-reaction is coupled to uptake of one proton, which in turn can facilitate second 2 O −  binding and subsequent reduction. Proton uptake coupled to metal ion reduction was demonstrated in the basic paper of Bull and Fee [28] and in more recent studies [29] [30].…”

Section: Superoxide Dismutase Activitymentioning

confidence: 89%

Superoxide Dismutase: Therapeutic Targets in SOD Related Pathology

Filip¹,

Albu²,

Zamosteanu³

2014

Health

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There are growing evidences on the role of adaptive mechanisms of all cell types in pathological processes: atherosclerosis, ischemic attack, bacterial infections, etc. All kinds of these processes involve as main mechanism oxidative stress. Aerobic organisms use oxygen in processes that accidentally or deliberately generate aggressive species for the biologic components in the form of radicals. Radicals were looked initially as "harmful" molecules and this is true for large quantities but in small or even moderate amounts these molecules prove to have a physiological role. Reactive species are highly reactive and as a consequence are short living species. Their impact is supposed to be limited in the proximity area of their formation. Instead recent evidences indicate their implications in cellular signaling suggesting that individual chemical properties of reactive species make a difference in their biological role. This paper presents superoxide, nitric oxide and peroxide radical generation under cellular changing conditions, the adapting behavior of the enzymes that synthesize and remove them as well as some therapeutic target in superoxide related pathology.

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“…The mechanism by which SODs achieve catalysis involves electron transfer to and from the redox-active metal site coupled with rapid proton transfers (PCET) [18], and proceeds via a ping-pong mechanism wherein the metal is fi rst reduced and then reoxidized by superoxide (Equations 1-3 …”

Section: Superoxide Dismutase Enzymesmentioning

confidence: 99%

“…Uptake of a proton upon reduction of the enzyme has been demonstrated for Mn/FeSODs and CuZnSODs [18,39,40], but not for NiSOD, which is assumed to function in an analogous manner. Figure 1 compares the pH dependence of k cat for various SODs.…”

Section: Superoxide Dismutase Enzymesmentioning

confidence: 99%