CATL 21 |
| This presentation will describe the application of oxidase reactions in producing selected target products using biocatalytic routes. Our research is focused on the synthesis of compounds such as antioxidants, using selected oxidase or peroxidase enzymes, and including a multi-enzyme bioprocess approach. This involves the rational design of biocatalytic routes to the target compounds, identification of suitable enzyme biocatalysts, and development of effective conditions for each step in the designed synthetic route. Optimization of each biocatalysis step, and incorporation of the steps as unit operations, allows us to develop efficient bioprocesses for the specific target products. Thus, a “tool-box” of biocatalytic reactions can be applied, including site-specific hydroxylation and oxidation, dimerisation, oligomerisation and depolymerisation. We include other enzymes such as lipases where, for instance, activation by acylation is required. The reactions described will include conversion of substrates such as ferulic acid and related phenolics, steroids, 8-hydroxyquinoline and benzofurans, producing hydroxylated and dimerised products or oligomers, all of which are novel antioxidants. The biocatalytic syntheses of such compounds is not straightforward and has not previously been elucidated. A key step in the synthesis of these compounds is controlled carbon-carbon bond formation, and we have achieved these biotransformations using oxidase biocatalysis and solvent engineering. The products have been characterised in terms of their structure and antioxidant activity. Rationalisation of the chemical structures of these novel products leads us to new understanding of the mechanisms of the oxidase reactions. The kinetics of the reactions using the immobilized biocatalysts in the small-scale bioreactors have been measured and used to develop a model of the multi-step process which enables prediction of scale-up conditions as well as allowing the exploration of new ways to use the biocatalytic unit operations in new synthetic routes. |
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Strategies in Enzymatic Oxidation Catalysis
8:30 AM-12:00 PM, Monday, August 20, 2007 BCEC -- 261, Oral
Catalysis & Surface Science Secretariat |