Barclay, Scott Sinclair;
(2000)
The production and use of cylohexanone monoxyegenase for Baeyer-Villiger biotransformations.
Doctoral thesis (Ph.D.), University College London.
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Abstract
Traditional chemical catalytic routes to optically pure materials are often inadequate, expensive and in some cases unknown. Optically pure lactones can form the starting material for a large number of drug classes. The Baeyer-Villiger reaction can be used to produce lactones from cyclic ketones. Using a biological catalyst (cyclohexanone monooxygenase) a more efficient, stereoselective and environmentally friendly route may be found. This thesis examines the production and use of the biocatalyst cyclohexanone monooxygenase from both the wild type organism A. calcoaceticus ( a known class II pathogen) and a recombinant Escherichia coli strain expressing the protein. The protocols have been developed to maximise the productivity of the fermentations of both organisms. Novel feeding strategies were developed for producing enzyme from A. calcoaceticus with an order of magnitude increase in productivity over the published methods. This research has shown that the production of cyclohexanone monooxygenase in both the wild type organism, A. calcoaceticus, and a recombinant E. coli is dependent on the feeding and induction strategy. In E. coli the productivity of the fermentation is greatly influenced by the growth rate at the time of induction while in A. calcoaceticus inducing growth substrate is required at the beginning of the fermentation if the enzyme is to be induced by a later substrate switch. The use of whole cells and crude homogenate from both organisms have been evaluated. Only whole cells from A. calcoaceticus were found to be of use due to the inability of E. coli cells to facilitate the reaction. The homogenate from E. coli was found to be most useful as a biocatalyst due to the overmetabolism of the lactone by A. calcoaceticus.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D. |
| Title: | The production and use of cylohexanone monoxyegenase for Baeyer-Villiger biotransformations. |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by Proquest |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10109314 |
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