TY - JOUR
T1 - Oxidation of lignans and lignin model compounds by laccase in aqueous solvent systems
AU - Mattinen, Maija-Liisa
AU - Maijala, Pekka
AU - Nousiainen, Paula
AU - Smeds, Annika
AU - Kontro, Jussi
AU - Sipilä, Jussi
AU - Tamminen, Tarja
AU - Willför, Stefan
AU - Viikari, Liisa
N1 - Funding Information:
The study was part of the LigniVal project with the BioRefine program funded by the Finnish Funding Agency for Technology and Innovation . Funding from Metso Power Oy, Oy Metsä-Botnia Ab, Stora Enso Oyj and Roal Oy is also acknowledged. Financial support was also obtained from the Academy of Finland (research grant no: 1127961 ). Päivi Matikainen and Tapani Suortti (VTT, Espoo, Finland) and Saskia Araújo (University of Helsinki, Helsinki, Finland) are thanked for skilful technical assistance.
PY - 2011/11
Y1 - 2011/11
N2 - The stability and activity of the low redox potential Melanocarpus albomyces laccase (MaL) in various aqueous organic (acetone, ethanol, propylene glycol, diethylene glycol monomethyl ether) solvent systems was studied spectrophotometrically using 2,6-dimethoxyphenol (2,6-DMP) as substrate. In addition, reactivity of the enzyme with two lignans; matairesinol (MR) and 7-hydroxymatairesinol (HMR), was examined by oxygen consumption measurements in the most potential aqueous organic solvent systems. Polymerization of the lignans by MaL was verified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). Polymerization of the higher molecular weight lignin model compound, dehydrogenation polymers (DHPs), was studied by SEC. The solubilities of industrial softwood and hardwood kraft lignins were evaluated as parameters for investigation of enzymatic modification in aqueous organic solvent systems. The functioning of MaL in different aqueous organic media was excellent. Propylene glycol and diethylene glycol monomethyl ether were better solvents than ethanol or acetone in enzymatic oxidations. Even though they were the best solvents for enzyme oxidation, ethanol and propylene glycol were selected for further tests because of their different physicochemical properties. The results obtained in this study for the use of laccase-catalysed reactions in organic solvents to improve the efficiency of lignin oxidation may be exploited in several applications and areas in which the solubility of the reactants or products is a limiting factor.
AB - The stability and activity of the low redox potential Melanocarpus albomyces laccase (MaL) in various aqueous organic (acetone, ethanol, propylene glycol, diethylene glycol monomethyl ether) solvent systems was studied spectrophotometrically using 2,6-dimethoxyphenol (2,6-DMP) as substrate. In addition, reactivity of the enzyme with two lignans; matairesinol (MR) and 7-hydroxymatairesinol (HMR), was examined by oxygen consumption measurements in the most potential aqueous organic solvent systems. Polymerization of the lignans by MaL was verified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). Polymerization of the higher molecular weight lignin model compound, dehydrogenation polymers (DHPs), was studied by SEC. The solubilities of industrial softwood and hardwood kraft lignins were evaluated as parameters for investigation of enzymatic modification in aqueous organic solvent systems. The functioning of MaL in different aqueous organic media was excellent. Propylene glycol and diethylene glycol monomethyl ether were better solvents than ethanol or acetone in enzymatic oxidations. Even though they were the best solvents for enzyme oxidation, ethanol and propylene glycol were selected for further tests because of their different physicochemical properties. The results obtained in this study for the use of laccase-catalysed reactions in organic solvents to improve the efficiency of lignin oxidation may be exploited in several applications and areas in which the solubility of the reactants or products is a limiting factor.
KW - Dehydrogenation polymers
KW - Laccase
KW - Lignans
KW - Lignin
KW - Melanocarpus albomyces
KW - Reactivity
KW - Solvent
UR - http://www.scopus.com/inward/record.url?scp=80052265675&partnerID=8YFLogxK
U2 - 10.1016/j.molcatb.2011.05.009
DO - 10.1016/j.molcatb.2011.05.009
M3 - Article
AN - SCOPUS:80052265675
SN - 1381-1177
VL - 72
SP - 122
EP - 129
JO - Journal of Molecular Catalysis B: Enzymatic
JF - Journal of Molecular Catalysis B: Enzymatic
IS - 3-4
ER -