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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Renewable Product Technology Research » Research » Publications at this Location » Publication #314694
Title: Laccase-mediator catalyzed conversion of model lignin compounds

Author
item Rich, Joseph
item Anderson, Amber
item LARSON, TROY - Augustana College

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/2015
Publication Date: 1/5/2016
Citation: Rich, J.O., Anderson, A.M., Larson, T.M. 2016. Laccase-mediator catalyzed conversion of model lignin compounds [abstract]. 12th Biotrans, Vienna University of Technology. 5:111-115.

Interpretive Summary:

Technical Abstract: Identifying suitable reaction conditions remains an important task in the development of practical enzyme catalysts. Laccases play an important role in the biological break down of lignin and have great potential in the deconstruction of lignocellulosic feedstocks. We examined 16 laccases, both commercially prepared and crude extracts, for their ability to oxidize veratryl alcohol in the presence of various solvents and mediators. While many of the literature reports have described single enzyme-mediator pairs, we will describe a combinatorial approach to the laccase-mediated system (LMS) where 16 enzymes were each paired with 30 different previously reported mediators. We determined the pH optimum (4.4–6.4) and operational temperature range (25–80 °C) for each enzyme. The LMS reaction was optimized to achieve near quantitative yields in the oxidation of veratryl alcohol to veratrylaldehyde. Although each of the mediators had been previously reported to serve as a laccase-mediator, it is clear that for a given substrate, it is necessary to examine a wide variety of enzyme-mediator combinations, and this combinatorial approach will enable the rapid identification of a suitable enzyme-mediator combination and optimization of reaction conditions. The application of the LMS for the modification of lignin model compounds, including novel biobased products from these reactions, will also be discussed. The application of the LMS for the modification of lignin model compounds, including novel biobased products from these reactions, will also be discussed. Specifically, we examined a variety of laccases, both commercially prepared and crude extracts, for their ability to oxidize three model lignol compounds (p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol). We identified both mediated and non-mediated laccase-catalyzed reactions that converted p-coumaryl alcohol and sinapyl alcohol to p hydroxybenzaldehyde and 2,6-dimethoxybenzoquinone. Interestingly, the products produced by the concerted action of the laccase mediator system on lignol substrates are the same as those produced by chemical catalytic approaches. The enzymatic approach affords the opportunity for a biological approach to the conversion of lignin to valuable specialty chemicals that have use in a variety of industrial, consumer, and pharmaceutical applications.