BIOT 25 |
| The use of FAD containing oxidases and dehydrogenases in biocatalysis is limited by the formation of reactive oxygen species (ROS) and their sometimes low activity with molecular oxygen as electron acceptor. Frequently, these FAD-containing oxidases show significant activity with electron acceptors other than oxygen. The engineering of a process using alternative electron acceptors circumvents the formation of ROS, but demands a regeneration system to avoid stoichiometric use of these substances. We coupled several artificial electron acceptors for oxidizing flavoenzymes to laccase as a regenerating enzyme to recycle the reduced form of the electron acceptor. Several tested flavoenzymes and laccase show complementary activity on most of these redox active substances, thus forming a regenerative cycle. For the study of the proposed regeneration system cellobiose dehydrogenase, and pyranose 2-oxidase were studied in coupled biotransformation experiments for the production of oxidized carbohydrate intermediates of industrial interest. The impact of several process parameters on specific productivity and operational stability were evaluated in batch reactions were found to have a significant influence on conversion rate and turnover stability. In conclusion it could be shown that the presented regeneration system works very well with different flavoenzymes, increased the specific productivity and enzyme stability significantly, and hence is applicable for a wide range of biotransformations employing flavoenzymes.
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Upstream Processing: Advances in Biocatalysis
8:00 AM-11:00 AM, Sunday, August 19, 2007 BCEC -- 107C, Oral
Division of Biochemical Technology |