TY - JOUR
T1 - Action of fungal laccases on lignin model compounds in organic solvents
AU - Maijala, Pekka
AU - Mattinen, Maija-Liisa
AU - Nousiainen, Paula
AU - Kontro, Jussi
AU - Asikkala, Janne
AU - Sipilä, Jussi
AU - Viikari, Liisa
N1 - Funding Information:
The study was part of the LigniVal project in the Tekes BioRefine program. Funding from Tekes, Metso Power Oy, Oy Metsä-Botnia Ab, Stora Enso Oyj and Roal Oy is acknowledged. Stefan Willför and Annika Smeds (Åbo Akademi University, Turku, Finland) are thanked for providing the lignans, and Kristiina Kruus (VTT, Espoo, Finland) for purified ThL and MaL laccases. Provision of TaLcc1, TaLcc2 and CtLcc1 laccases by Roal Oy is acknowledged. Comments on MaL and TaLcc1 structures by Nina Hakulinen (University of Eastern Finland, Joensuu, Finland) are gratefully acknowledged. Pekka Maijala is partially supported by the Academy of Finland, project no: 1127961. In addition Päivi Matikainen (VTT) and Saskia Araújo (University of Helsinki) are thanked for the technical assistance.
PY - 2012/4
Y1 - 2012/4
N2 - The stability and reactivity of five different thermostable fungal laccases from the species Trametes hirsuta, Melanocarpus albomyces, Thielavia arenaria (two laccases) and Chaetomium thermophilum were investigated in the presence of organic solvents. Oxidations of small organic phenolic compounds, matairesinol and 7-hydroxymatairesinol lignans, as well as synthetic lignin dehydrogenation polymer DHP in aqueous solutions of ethanol and propylene glycol solvents were investigated using analysis of oxidation rates, high performance liquid chromatography and size-exclusion chromatography. The laccases showed variability in their solvent tolerance. The redox potential of the laccases appeared not to be the main factor determining the efficiency of the polymerization reactions of complex phenolic model compounds in aqueous organic solutions. Nuclear magnetic resonance spectroscopic analysis of laccase treated DHP in 50% propylene glycol indicated that the formation of new biphenylic 5-5′ structures was favored in laccase-catalyzed radical coupling reactions over the other possible reactions through the phenolic groups forming new 5O4 ether bonds. The polymerization reactions took place even at high concentrations of solvents, which already inhibited the enzyme activity, encouraging enzymatic upgrading of lignin in organic solvents to be studied further. Thus, it was confirmed that thermostable laccases are potential enzymes for various industrial applications where organic solvents are required for the reaction systems.
AB - The stability and reactivity of five different thermostable fungal laccases from the species Trametes hirsuta, Melanocarpus albomyces, Thielavia arenaria (two laccases) and Chaetomium thermophilum were investigated in the presence of organic solvents. Oxidations of small organic phenolic compounds, matairesinol and 7-hydroxymatairesinol lignans, as well as synthetic lignin dehydrogenation polymer DHP in aqueous solutions of ethanol and propylene glycol solvents were investigated using analysis of oxidation rates, high performance liquid chromatography and size-exclusion chromatography. The laccases showed variability in their solvent tolerance. The redox potential of the laccases appeared not to be the main factor determining the efficiency of the polymerization reactions of complex phenolic model compounds in aqueous organic solutions. Nuclear magnetic resonance spectroscopic analysis of laccase treated DHP in 50% propylene glycol indicated that the formation of new biphenylic 5-5′ structures was favored in laccase-catalyzed radical coupling reactions over the other possible reactions through the phenolic groups forming new 5O4 ether bonds. The polymerization reactions took place even at high concentrations of solvents, which already inhibited the enzyme activity, encouraging enzymatic upgrading of lignin in organic solvents to be studied further. Thus, it was confirmed that thermostable laccases are potential enzymes for various industrial applications where organic solvents are required for the reaction systems.
KW - Laccase
KW - Lignan
KW - Lignin
KW - Reactivity
KW - Solvent
KW - Stability
UR - http://www.scopus.com/inward/record.url?scp=84855770873&partnerID=8YFLogxK
U2 - 10.1016/j.molcatb.2011.12.009
DO - 10.1016/j.molcatb.2011.12.009
M3 - Article
AN - SCOPUS:84855770873
SN - 1381-1177
VL - 76
SP - 59
EP - 67
JO - Journal of Molecular Catalysis B: Enzymatic
JF - Journal of Molecular Catalysis B: Enzymatic
ER -