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Oral
Presentation 6-01 Proteases and the
Extracellular Lignin Depolymerase Activity
from Trametes cingulata Yi-ru Chen, Todd B. Vinzant1, Stephen R. Decker1 Ed Jennings1, Michael E. Himmel1 and Simo Sarkanen
Kaufert
Laboratory
University
of Minnesota
St.
Paul, MN 55108
1National
Bioenergy Center Biotechnology Division for Fuels and Chemicals National Renewable Energy Laboratory 1617 Cole Boulevard Golden, CO 80401 Telephone: (612) 624-6227; Fax: (612) 625-6286; E-mail: ssarka@cnr.umn.edu
The
concomitant degradation of lignins can improve the efficiency with which
polysaccharides in wood and plant materials are optimally converted to
biofuels. It was reported in 1983 that
a lignin depolymerizing enzyme called lignin peroxidase had been isolated for
the first time from a white-rot fungus.
Thereafter, manganese-dependent peroxidase and laccase (acting through
mediators) were also implicated in lignin depolymerization in vivo. However, none of
these enzymes has been shown to be capable of degrading polymeric lignin
preparations completely in vitro: their catalytic activities engender
competition between polymerization and depolymerization. Recently an enzyme was
isolated from the white-rot fungus Trametes
cingulat, which appears to degrade polymeric lignin preparations without
any sign of competing polymerization.
This lignin depolymerase is neither a peroxidase nor a laccase. However, its susceptibility to the effects
of white-rot fungal proteases has confounded attempts to secure enough of the
active enzyme for adequate characterization.
Accordingly, the levels of extracellular protease activity in T. cingulata cultures have been
monitored during primary growth and subsequent idiophasic development of the
microorganism. Through these means, a
period of time was sought where the effects of protease activity upon lignin
depolymerase would be at a minimum.
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