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Oral Presentation 6-04 Effects of Pretreatment on the Activity of Enzymes
in Plants: Cellulase
Enzymes and Ribulose Diphosphate Carboxylase Farzaneh Teymouri and Bruce E. Dale
Department of Chemical Engineering and Materials ScienceRoom 2527, Engineering Building
Michigan State University, East Lansing, MI 48824-1226
Telephone: (517) 353-6777; Fax: (517) 432-1105; E-mail: bdale@egr.msu.edu
A
major economic obstacle in bioconverting lignocellulosic materials to ethanol
and other products is high cellulase costs.
These costs could conceivably be reduced by genetically transforming
plants with cellulase genes to produce the desired enzymes, perhaps even
releasing active cellulases from the plants during bioconversion. Lignocellulose conversion economics might
also be enhanced by coproducing valuable proteins in the lignocellulosic
biomass. Under both scenarios,
retention of protein activity during processing is a pivotal consideration.
We
measured the effects of various lignocellulose pretreatments employing a range
of treatment pH values and temperatures on the activity of several
plant-produced enzymes. Enzyme
activities and plant materials included transgenic tobacco plants expressing E1
(endoglucanase from Acidothermus cellulolyticus). The E1 activity was measured in fresh
(green) tobacco leaves, in dried leaves and finally in pretreated leaves to
characterize the effects of various pretreatments on E1 activity. Maize transformed with the cellobiohydrolase
(CBHI) gene from Trichoderma reesei and the effects of pretreatment on
enzyme activity were determined.
Finally, we chose ribulose diphosphate carboxylase (Rubisco) from
tobacco and alfalfa plants as a marker to probe the effects of pretreatment on the
plants’ own bioactive proteins. Several
pretreatments appear to offer hope for preserving protein activity during
processing.
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