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Chirivì C, Fontana G, Monti D, Ottolina G, Riva S, Danieli B. The Quest for New Mild and Selective Modifications of Natural Structures: Laccase-Catalysed Oxidation of Ergot Alkaloids Leads to Unexpected Stereoselective C-4 Hydroxylation. Chemistry 2012; 18:10355-61. [DOI: 10.1002/chem.201201076] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Indexed: 11/06/2022]
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52
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Uthandi S, Prunetti L, De Vera IMS, Fanucci GE, Angerhofer A, Maupin-Furlow JA. Enhanced archaeal laccase production in recombinant Escherichia coli by modification of N-terminal propeptide and twin arginine translocation motifs. J Ind Microbiol Biotechnol 2012; 39:1523-32. [PMID: 22752793 DOI: 10.1007/s10295-012-1152-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 05/28/2012] [Indexed: 11/29/2022]
Abstract
Laccases are multicopper oxidases that couple the oxidation of phenolic polymers to the reduction of molecular oxygen. While an archaeal laccase has only recently been described (LccA from the culture broth of Haloferax volcanii), this enzyme appears promising for biotechnology applications based on its robust bilirubin oxidase and laccase activities as well as its ability to withstand prolonged exposure to extreme conditions. To further optimize LccA productivity and develop an option for LccA purification from whole cells, the encoding gene was modified through deletion of the twin-arginine translocation motif and N-terminal propeptide, and the modified genes were expressed in Escherichia coli. With this approach, LccA was readily purified (overall yield up to 54 %) from the soluble fraction of E. coli as a 74-kDa monomer with syringaldazine oxidizing activity as high as 33 U mg(-1). LccA proteins prepared from H. volcanii culture broth and the soluble fraction of E. coli cells were compared by ICP-AES, EPR, DSC, CD, and UV-Vis spectroscopy and found to have a similar folding pattern with T (m) values and a rich β-sheet structure analogous to other multicopper oxidases. However, in contrast to the H. volcanii-purified LccA, which was loaded with copper, copper was not fully incorporated into the type-I Cu center of E. coli purified LccA, thus, providing insight into avenues for further optimization.
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Affiliation(s)
- Sivakumar Uthandi
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611-0700, USA.
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53
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Weng SS, Ku KL, Lai HT. The implication of mediators for enhancement of laccase oxidation of sulfonamide antibiotics. BIORESOURCE TECHNOLOGY 2012; 113:259-264. [PMID: 22257859 DOI: 10.1016/j.biortech.2011.12.111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/19/2011] [Accepted: 12/20/2011] [Indexed: 05/31/2023]
Abstract
In this study, the transformation of sulfonamide antibiotics (SAs, 50 mg L(-1)) was investigated in systems consisting of a fungal laccase (6 IU) and six mediators (1mM). The results illustrate that the laccase had limited effect on the removal of sulfadimethoxine and sulfamonomethoxine. However, laccase oxidation with the mediators (LMS) led to significant declines of the SAs. Two mediators, 2-2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and violuric acid, provided the fastest transformations of SAs in LMS, with t(1/2)s of 1.8-4.1 min; slower transformations in syringaldehyde and 4-hydroxybenzyl alcohol, with t(1/2)s of 19.0-131 min; and the slowest or no significant decline in 4-hydroxyacetophenone and 4-cyanophenol, with t(1/2)s > 330 min. The decline of the re-added SAs in LMS was slower than that of the first addition. De-aniline and oxidative coupling are the two detectable pathways for the transformation of SAs. The results indicated that some mediators enhanced laccase oxidation of the SAs.
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Affiliation(s)
- Shin-Sian Weng
- Department of Aquatic Biosciences, National Chiayi University, 300 University Rd., Chiayi 60004, Taiwan
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54
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Aracri E, Valls C, Vidal T. Paper strength improvement by oxidative modification of sisal cellulose fibers with laccase–TEMPO system: Influence of the process variables. Carbohydr Polym 2012. [DOI: 10.1016/j.carbpol.2012.01.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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55
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Chen Y, Wan J, Ma Y, Tang B, Han W, Ragauskas AJ. Modification of old corrugated container pulp with laccase and laccase-mediator system. BIORESOURCE TECHNOLOGY 2012; 110:297-301. [PMID: 22326330 DOI: 10.1016/j.biortech.2011.12.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 05/31/2023]
Abstract
Modification of the physical properties of old corrugated container (OCC) pulp with laccase or a laccase-mediator (ABTS, HBT, VA) system was investigated under select enzymatic concentrations and reaction times. The optimal conditions for laccase treatment shown to be using a laccase dose of 160U/g o.d. pulp, a treatment time of 20h at 25°C, pH 7 with a pulp consistency of 5%. Results showed that the Lac-HBT treated OCC pulp gave the best strength properties, improving tensile strength by 15.7%. The increase in the carboxyl group content of OCC laccase or Lac-HBT treated pulp led to the increase in the swelling ability and bonding between fibers. Microscope images showed the fiber surface became rougher and more collapsible after Lac-HBT treatment. FT-IR data showed that new carboxylic acid groups were formed during Lac-HBT treatment.
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Affiliation(s)
- Yangmei Chen
- College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006, PR China
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57
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Fu J, Nyanhongo GS, Gübitz GM, Cavaco-Paulo A, Kim S. Enzymatic colouration with laccase and peroxidases: Recent progress. BIOCATAL BIOTRANSFOR 2012. [DOI: 10.3109/10242422.2012.649563] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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58
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Vila C, Barneto AG, Fillat A, Vidal T, Ariza J. Use of thermogravimetric analysis to monitor the effects of natural laccase mediators on flax pulp. BIORESOURCE TECHNOLOGY 2011; 102:6554-6561. [PMID: 21498071 DOI: 10.1016/j.biortech.2011.03.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 03/18/2011] [Accepted: 03/20/2011] [Indexed: 05/30/2023]
Abstract
The effects of 1-hydroxybenzotriazole (HBT) and the natural laccase mediators gallic acid, caffeic acid and p-hydroxybenzoic acid, on the enzymatic bleaching of flax pulp were compared. The treatment was performed under atmospheric air and oxygen pressure, and, for the first time, monitored by thermogravimetric analysis (TGA) for comparison with chemical analysis, FTIR and X-ray diffraction (XRD) spectroscopies. Thermogravimetric data were simulated by applying a nucleation kinetic equation to a combustion model based on four pseudo-components (hemicellulose, amorphous and crystalline cellulose, and lignin). The results thus obtained show that the effects of the natural mediators are similar to those of HBT and lead to increased order in cellulose microfibril surfaces. An increase in pulp crystallinity was additionally exposed by the XRD and FTIR techniques, and a reduction in microfibril equatorial size by the XRD patterns. Simulated DTG curves were used to determine the kinetic parameters for thermal degradation.
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Affiliation(s)
- Carlos Vila
- Department of Textile and Paper Engineering, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain
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59
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Monti D, Ottolina G, Carrea G, Riva S. Redox Reactions Catalyzed by Isolated Enzymes. Chem Rev 2011; 111:4111-40. [DOI: 10.1021/cr100334x] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Daniela Monti
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Gianluca Ottolina
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Giacomo Carrea
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Sergio Riva
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
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60
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Mendoza L, Mamo G, Flores N, Gimenez A, Hatti-Kaul R. Laccase mediator system for activation of agarose gel: Application for immobilization of proteins. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.molcatb.2010.11.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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61
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Zhang P, Wang C, Chen Z, Li H. Acetylacetone–metal catalyst modified by pyridinium salt group applied to the NHPI-catalyzed oxidation of cholesteryl acetate. Catal Sci Technol 2011. [DOI: 10.1039/c1cy00186h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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62
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Moldes D, Cadena EM, Vidal T. Biobleaching of eucalypt kraft pulp with a two laccase-mediator stages sequence. BIORESOURCE TECHNOLOGY 2010; 101:6924-6929. [PMID: 20430613 DOI: 10.1016/j.biortech.2010.03.127] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 03/29/2010] [Accepted: 03/30/2010] [Indexed: 05/29/2023]
Abstract
A new biobleaching sequence, with two enzymatic stages based on the application of laccase-mediator systems, was tested (L(1)EL(2)QPo) in order to increase the effectiveness of enzyme delignification on eucalypt kraft pulp. Different synthetic -1-hydroxybenzotriazole (HBT) and violuric acid (VA) - and natural - syringaldehyde (SyAl) - mediators were used in the laccase stages and the biobleached pulp were compared in terms of chemical, optical and physico-mechanical properties. The pulp bleached with HBT or VA showed similar delignification (64.1% and 65.9% respectively) and optical properties (86.4% and 86.1% ISO brightness respectively) than an industrial TCF pulp (68.3% delignification and 84.8% ISO brightness). SyAl improved these properties in a lower extent (56.71% delignification and 80.52% ISO brightness). Regarding physico-mechanical properties of pulp, the biobleaching sequence had no a negative effect, even some slight improvements were observed in very specific cases.
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Affiliation(s)
- D Moldes
- Department of Textile and Paper Engineering, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain
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63
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Zumárraga M, Plou FJ, García-Arellano H, Ballesteros A, Alcalde M. Bioremediation of polycyclic aromatic hydrocarbons by fungal laccases engineered by directed evolution. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420701444272] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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64
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65
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Coseri S. Phthalimide‐N‐oxyl (PINO) Radical, a Powerful Catalytic Agent: Its Generation and Versatility Towards Various Organic Substrates. CATALYSIS REVIEWS-SCIENCE AND ENGINEERING 2009. [DOI: 10.1080/01614940902743841] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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66
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Witayakran S, Ragauskas AJ. Modification of high-lignin softwood kraft pulp with laccase and amino acids. Enzyme Microb Technol 2009. [DOI: 10.1016/j.enzmictec.2008.10.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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67
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Witayakran S, Ragauskas AJ. Cocatalytic Enzyme System for the Michael Addition Reaction of in-situ-Generatedortho-Quinones. European J Org Chem 2009. [DOI: 10.1002/ejoc.200800791] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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68
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Kunamneni A, Camarero S, García-Burgos C, Plou FJ, Ballesteros A, Alcalde M. Engineering and Applications of fungal laccases for organic synthesis. Microb Cell Fact 2008; 7:32. [PMID: 19019256 PMCID: PMC2613868 DOI: 10.1186/1475-2859-7-32] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 11/20/2008] [Indexed: 11/10/2022] Open
Abstract
Laccases are multi-copper containing oxidases (EC 1.10.3.2), widely distributed in fungi, higher plants and bacteria. Laccase catalyses the oxidation of phenols, polyphenols and anilines by one-electron abstraction, with the concomitant reduction of oxygen to water in a four-electron transfer process. In the presence of small redox mediators, laccase offers a broader repertory of oxidations including non-phenolic substrates. Hence, fungal laccases are considered as ideal green catalysts of great biotechnological impact due to their few requirements (they only require air, and they produce water as the only by-product) and their broad substrate specificity, including direct bioelectrocatalysis. Thus, laccases and/or laccase-mediator systems find potential applications in bioremediation, paper pulp bleaching, finishing of textiles, bio-fuel cells and more. Significantly, laccases can be used in organic synthesis, as they can perform exquisite transformations ranging from the oxidation of functional groups to the heteromolecular coupling for production of new antibiotics derivatives, or the catalysis of key steps in the synthesis of complex natural products. In this review, the application of fungal laccases and their engineering by rational design and directed evolution for organic synthesis purposes are discussed.
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Affiliation(s)
- Adinarayana Kunamneni
- Departamento de Biocatálisis, Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, 28049 Madrid, Spain.
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70
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Moldes D, Díaz M, Tzanov T, Vidal T. Comparative study of the efficiency of synthetic and natural mediators in laccase-assisted bleaching of eucalyptus kraft pulp. BIORESOURCE TECHNOLOGY 2008; 99:7959-65. [PMID: 18499450 DOI: 10.1016/j.biortech.2008.04.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Revised: 03/31/2008] [Accepted: 04/03/2008] [Indexed: 05/03/2023]
Abstract
The natural phenolic compounds syringaldehyde and vanillin were compared to the synthetic mediators 1-hydroxybenzotriazole, violuric acid and promazine in terms of boosting efficiency in a laccase-assisted biobleaching of eucalyptus kraft pulp. Violuric acid and 1-hydroxybenzotriazole revealed to be the most effective mediators of the bioprocess. Nevertheless, laccase-syringaldehyde system also improved the final pulp properties (28% delignification and 63.5% ISO brightness) compared to the process without mediator (23% and 61.5% respectively), in addition to insignificant denaturation effect over laccase. The efficiency of the biobleaching process was further related to changes in non-conventionally used optical and chromatic parameters of pulp, such as (L*), chroma (C*) and dye removal index (DRI) showing good correlation. Adverse coupling reactions of the natural phenolic mediators on pulp lignin were predicted by electrochemical studies, demonstrating the complexity of the laccase-mediator reaction on pulp.
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Affiliation(s)
- D Moldes
- Department of Textile and Paper Engineering, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain.
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71
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Brogioni B, Biglino D, Sinicropi A, Reijerse EJ, Giardina P, Sannia G, Lubitz W, Basosi R, Pogni R. Characterization of radical intermediates in laccase-mediator systems. A multifrequency EPR, ENDOR and DFT/PCM investigation. Phys Chem Chem Phys 2008; 10:7284-92. [PMID: 19060974 DOI: 10.1039/b812096j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Suitable low molecular-weight compounds, called mediators, can be used in combination with the phenol-oxidase enzyme laccase to indirectly oxidize large organic substrates, such as environmental pollutants, which are not laccase natural substrates. The oxidation of two different synthetic redox mediators, violuric acid (VIO) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) has been studied under catalysis of two laccases from white-rot fungi (Trametes versicolor and Pleurotus ostreatus). VIO was selected as a prototype of the -NOH type of mediators and compared to ABTS, a well-known two-step redox system. To characterize the radical intermediates formed from both mediators after the enzymatic oxidation, a multifrequency EPR approach has been adopted. The radical species have been investigated employing 9.4 GHz (X-band), 34 GHz (Q-band) and 244 GHz (high field) EPR and pulse electron nuclear double resonance (ENDOR) techniques. Theoretical calculations based on density functional theory (DFT/PCM) have been performed to support and further interpret the experimental EPR and ENDOR data. This integrated approach allowed us to obtain a complete characterization of both radicals and to elucidate the type of the radical state (neutral or cationic).
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Affiliation(s)
- Barbara Brogioni
- Department of Chemistry, University of Siena, Via Aldo Moro, 53100, Siena, Italy
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72
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Tadesse MA, D'Annibale A, Galli C, Gentili P, Sergi F. An assessment of the relative contributions of redox and steric issues to laccase specificity towards putative substrates. Org Biomol Chem 2008; 6:868-78. [DOI: 10.1039/b716002j] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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74
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Coniglio A, Galli C, Gentili P, Vadalà R. Oxidation of amides by laccase-generated aminoxyl radicals. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.molcatb.2007.09.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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75
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Witayakran S, Gelbaum L, Ragauskas AJ. Cascade synthesis of benzofuran derivatives via laccase oxidation–Michael addition. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.08.066] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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76
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Morozova OV, Shumakovich GP, Shleev SV, Yaropolov YI. Laccase-mediator systems and their applications: A review. APPL BIOCHEM MICRO+ 2007. [DOI: 10.1134/s0003683807050055] [Citation(s) in RCA: 378] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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77
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78
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Shumakovich GP, Shleev SV, Morozova OV, Khohlov PS, Gazaryan IG, Yaropolov AI. Electrochemistry and kinetics of fungal laccase mediators. Bioelectrochemistry 2006; 69:16-24. [PMID: 16318928 DOI: 10.1016/j.bioelechem.2005.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2005] [Revised: 10/03/2005] [Accepted: 10/05/2005] [Indexed: 11/17/2022]
Abstract
The screening of potential redox mediators for laccase was performed using homogeneous Trametes hirsuta laccase. Heterogeneous (electrochemical) and homogeneous (oxidation by laccase) reactions of the different types of the enhancers (mediators) of the enzyme were investigated. It was discovered that derivatives of phenyl-methyl-pyrazolones and benzoic acid, as well as N-hydroxynaphthalimide were efficient substrates for the laccase. The characterization of several representatives from each class was carried out using electrochemical and enzyme kinetics methods. The kinetic parameters for the oxidation of phenyl-methyl-pyrazolones and 3-(6-hylroxy)-aminobenzoic acid were comparable to those for 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) oxidation by the laccase, whereas the rate of enzymatic oxidation of N-hydroxynaphthalimide was sufficiently lower. Electrochemical experiments demonstrated that only oxidation of phenyl-methyl-pyrazolones and N-hydroxynaphthalimide yielded several high-potential intermediates capable of oxidizing veratryl alcohol, which was used as a lignin model substrate, whereas derivatives of benzoic acid showed low-potential intermediate, which was not able to oxidized lignin model compound. Phenyl-methyl-pyrazolones was about 50% as effective in degrading veratryl alcohol compared to ABTS as judged from HPLC kinetic studies, whereas N-hydroxynaphthalimide showed the same efficiency as ABTS. Phenyl-methyl-pyrazolones and hydroxynaphthalimides may be of commercial interest for oxidoreductase-catalyzed biodegradation of different xenobiotics.
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Affiliation(s)
- G P Shumakovich
- Laboratory of Chemical Enzymology, A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky Pr. 33, 119071 Moscow, Russia
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79
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In search for practical advantages from the immobilisation of an enzyme: the case of laccase. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.molcatb.2006.04.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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80
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Arends IW, Li YX, Ausan R, Sheldon RA. Comparison of TEMPO and its derivatives as mediators in laccase catalysed oxidation of alcohols. Tetrahedron 2006. [DOI: 10.1016/j.tet.2005.12.076] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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81
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Riva S. Laccases: blue enzymes for green chemistry. Trends Biotechnol 2006; 24:219-26. [PMID: 16574262 DOI: 10.1016/j.tibtech.2006.03.006] [Citation(s) in RCA: 732] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 01/18/2006] [Accepted: 03/15/2006] [Indexed: 11/18/2022]
Abstract
Laccases are oxidoreductases belonging to the multinuclear copper-containing oxidases; they catalyse the monoelectronic oxidation of substrates at the expense of molecular oxygen. Interest in these essentially "eco-friendly" enzymes--they work with air and produce water as the only by-product--has grown significantly in recent years: their uses span from the textile to the pulp and paper industries, and from food applications to bioremediation processes. Laccases also have uses in organic synthesis, where their typical substrates are phenols and amines, and the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. Here, we provide a brief discussion of this interesting group of enzymes, increased knowledge of which will promote laccase-based industrial processes in the future.
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Affiliation(s)
- Sergio Riva
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milan, Italy.
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82
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d’Acunzo F, Galli C, Gentili P, Sergi F. Mechanistic and steric issues in the oxidation of phenolic and non-phenolic compounds by laccase or laccase-mediator systems. The case of bifunctional substrates. NEW J CHEM 2006. [DOI: 10.1039/b516719a] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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83
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84
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Brandi P, Galli C, Gentili P. Kinetic Study of the Hydrogen Abstraction Reaction of the Benzotriazole-N-oxyl Radical (BTNO) with H-Donor Substrates. J Org Chem 2005; 70:9521-8. [PMID: 16268628 DOI: 10.1021/jo051615n] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Reaction: see text]. The aminoxyl radical (>N-O*) BTNO (benzotriazole-N-oxyl) has been generated by the oxidation of 1-hydroxybenzotriazole (HBT; >N-OH) with a Ce(IV) salt in MeCN. BTNO presents a broad absorption band with lambda(max) 474 nm and epsilon 1840 M(-1) cm(-1), and spontaneously decays with a first-order rate constant of 6.3 x 10(-3) s(-1) in MeCN at 25 degrees C. Characterization of BTNO radical by EPR, laser flash photolysis, and cyclic voltammetry is provided. The spontaneous decay of BTNO is strongly accelerated in the presence of H-donor substrates such as alkylarenes, benzyl and allyl alcohols, and alkanols, and rate constants of H-abstraction by BTNO from a number of substrates have been spectroscopically investigated at 25 degrees C. The kinetic isotope effect confirms the H-abstraction step as rate-determining. Activation parameters have been measured in the 15-40 degrees C range with selected substrates. A correlation between E(a) and BDE(C-H) (C-H bond dissociation energy) for a small series of H-donors has been obtained according to the Evans-Polanyi equation, giving alpha = 0.44. From this plot, the experimentally unavailable BDE(C-H) of benzyl alcohol can be extrapolated, as ca. 79 kcal/mol. With respect to the H-abstraction step, peculiar differences in the DeltaS++ parameter emerge between an alkylarene, ArC(H)R2, and a benzyl alcohol, ArC(H)(OH)R. The data acquired on the H-abstraction reactivity of BTNO are compared with those recently reported for the aminoxyl radical PINO (phthalimide-N-oxyl), generated from N-hydroxyphthalimide (HPI). The higher reactivity of radical PINO is explained on the basis of the higher energy of the NO-H bond of HPI, as compared with that of HBT (88 vs ca. 85 kcal/mol, respectively), which is formed on H-abstraction from the RH substrate.
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Affiliation(s)
- Paolo Brandi
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, 00185 Roma, Italy
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Branchi B, Galli C, Gentili P. Kinetics of oxidation of benzyl alcohols by the dication and radical cation of ABTS. Comparison with laccase–ABTS oxidations: an apparent paradox. Org Biomol Chem 2005; 3:2604-14. [PMID: 15999194 DOI: 10.1039/b504199f] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Laccase, a blue copper oxidase, in view of its moderate redox potential can oxidise only phenolic compounds by electron-transfer. However, in the presence of ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) as a redox mediator, laccase reacts with the more difficult to oxidise non-phenolic substrates, such as benzyl alcohols. The role of ABTS in these mediated oxidations is investigated. Redox interaction with laccase could produce in situ two reactive intermediates from ABTS, namely ABTS++ or ABTS*+. These species have been independently generated by oxidation with Ce(iv) or Co(iii) salts, respectively, and their efficiency as monoelectronic oxidants tested in a kinetic study towards a series of non-phenolic substrates; a Marcus treatment is provided in the case of ABTS++. On these grounds, intervention of ABTS++ as a reactive intermediate in laccase-ABTS oxidations appears unlikely, because the experimental conditions under which ABTS++ is unambiguously generated, and survives long enough to serve as a diffusible mediator, are too harsh (2 M H2SO4 solution) and incompatible with the operation of the enzyme. Likewise, ABTS*+ seems an intermediate of limited importance in laccase-ABTS oxidations, because this weaker monoelectronic oxidant is unable to react directly with many of the non-phenolic substrates that laccase-ABTS can oxidise. To solve this paradox, it is alternatively suggested that degradation by-products of either ABTS++ or ABTS*+ are formed in situ by hydrolysis during the laccase-ABTS reactions, and may be responsible for the observed oxidation of non-phenolics.
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Affiliation(s)
- Barbara Branchi
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, P. le A. Moro 5, I-00185 Roma, Italy
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Astolfi P, Brandi P, Galli C, Gentili P, Gerini MF, Greci L, Lanzalunga O. New mediators for the enzyme laccase: mechanistic features and selectivity in the oxidation of non-phenolic substrates. NEW J CHEM 2005. [DOI: 10.1039/b507657a] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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