Autoreduction and aggregation of fungal laccase in solution phase: possible correlation with a resting form of laccase

Shleev, Sergey; Reimann, C.T.; Сереженков, В. А.; Burbaev, D. Sh.; Yaropolov, A. I.; Gorton, Lo; Ruzgas, Tautgirdas

doi:10.1016/j.biochi.2006.02.007

Cited by 29 publications

(19 citation statements)

References 37 publications

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“…Taking into account the many intermediates of MCO described in the literature (NI, PI, fully reduced enzyme (Red), and oxidized resting form, Ox), which have different structures of the Cu-T23 cluster [1,9,13,14,20], at least four E T23 values can be expected. Moreover, when NI is transformed to the Red three IET steps occur, so at least two intermediates with partly reduced Cu-T23 cluster with unknown structures are expected.…”

Section: Discussionmentioning

confidence: 99%

“…The slow IET might also be responsible for slow formation of different resting forms of the enzyme [1,9,13,14] due to spontaneous changes of the cluster with concomitant reduction of E T23 . Even if oxidation level of the Cu ions in the Ox and NI states of the enzyme are identical, the redox potentials of these intermediates are not necessarily close because the cluster geometry and ligand environment may be quite different.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, the presence of a slow IET (Fig. 1, process 2) for certain forms of MCOs, e.g., for inhibited enzymes [11,12] and for their resting forms [1,9,13,14], has been also postulated. This observation was further corroborated by detailed bioelectrochemical studies of adsorbed high-redoxpotential Lc and Box.…”

Section: Introductionmentioning

confidence: 99%

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On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

et al. 2012

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The catalytic cycle of multicopper oxidases (MCOs) involves intramolecular electron transfer (IET) from the Cu‐T1 copper ion, which is the primary site of the one‐electron oxidations of the substrate, to the trinuclear copper cluster (TNC), which is the site of the four‐electron reduction of dioxygen to water. In this study we report a detailed characterization of the kinetic and electrochemical properties of bilirubin oxidase (BOx) – a member of the MCO family. The experimental results strongly indicate that under certain conditions, e.g. in alkaline solutions, the IET can be the rate‐limiting step in the BOx catalytic cycle. The data also suggest that one of the catalytically relevant intermediates (most likely characterized by an intermediate oxidation state of the TNC) formed during the catalytic cycle of BOx has a redox potential close to 0.4 V, indicating an uphill IET process from the T1 copper site (0.7 V) to the Cu‐T23. These suggestions are supported by calculations of the IET rate, based on the experimentally observed Gibbs free energy change and theoretical estimates of reorganization energy obtained by combined quantum and molecular mechanical (QM/MM) calculations.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

et al. 2012

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“…The biocatalytic oxidation of ABTS should also occur even if resting forms of ThLc are formed on bare Au surfaces. It is well known that resting forms (both the resting oxidized form 2 and the resting partially reduced states 27 ) in the presence of both substrates will be transformed into the native intermediate (i.e., the catalytically relevant form of MCOs 2,47 ). Even though the rate of this transformation is very low (only 1 s −1 ), 47 3600 s experiments (as demonstrated in Figure 4) should be long enough to transfer all resting ThLc molecules into the active enzyme.…”

Section: Mg Mmentioning

confidence: 99%

“…The preparations were thawed and airsaturated for 2 h before use in order to avoid the possible presence of resting forms, viz., partially reduced enzymes. 27 The concentration of Lc and BOx was measured spectrophotometrically at 228.5 and 234.5 nm using BSA as a standard. 28 Enzyme Assay and Kinetic Studies.…”

Section: ■ Introductionmentioning

confidence: 99%

Interfacial Behavior and Activity of Laccase and Bilirubin Oxidase on Bare Gold Surfaces

et al. 2014

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Two blue multicopper oxidases (MCOs) (viz. Trametes hirsuta laccase (ThLc) and Myrothecium verrucaria bilirubin oxidase (MvBOx)) were immobilized on bare polycrystalline gold (Au) surfaces by direct adsorption from both dilute and concentrated enzyme solutions. The adsorption was studied in situ by means of null ellipsometry. Moreover, both enzyme-modified and bare Au electrodes were investigated in detail by atomic force microscopy (AFM) as well as electrochemically. When adsorbed from dilute solutions (0.125 and 0.25 mg mL −1 in the cases of ThLc and MvBOx, respectively), the amounts of enzyme per unit area were determined to be ca. 1.7 and 4.8 pmol cm −2 , whereas the protein film thicknesses were determined to be 29 and 30 Å for ThLc and MvBOx, respectively. A wellpronounced bioelectrocatalytic reduction of molecular oxygen (O 2 ) was observed on MvBOx/Au biocathodes, whereas this was not the case for ThLc-modified Au electrodes (i.e., adsorbed ThLc was catalytically inactive). The initially observed apparent k cat app values for adsorbed MvBOx and the enzyme in solution were found to be very close to each other (viz. 54 and 58 s −1

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Synthetic Applications of Laccase in Green Chemistry

Witayakran¹,

Ragauskas²

2009

Adv Synth Catal

304

175

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Laccases (benzenediol:oxygen oxidoreductase, EC 1.10.3.2), multi‐copper‐containing oxidoreductase enzymes, are able to catalyze the oxidation of various low‐molecular weight compounds, specifically, phenols and anilines, while concomitantly reducing molecular oxygen to water. Because of their high stability, selectivity for phenolic substructures, and mild reaction conditions, laccases are attractive for fine chemical synthesis. This review provides a discussion of the recent applications of this interesting enzyme in synthetic chemistry, including laccase and laccase‐mediator catalyzed reactions. In addition, the review also includes a brief discussion of the distribution of laccase in nature, enzyme structure, and the catalytic mechanism which are of relevance to their applications as biocatalysts.

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Autoreduction and aggregation of fungal laccase in solution phase: possible correlation with a resting form of laccase

Cited by 29 publications

References 37 publications

On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

Interfacial Behavior and Activity of Laccase and Bilirubin Oxidase on Bare Gold Surfaces

Synthetic Applications of Laccase in Green Chemistry

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