Engineering a highly enantioselective horseradish peroxidase by directed evolution
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2009.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2011
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| Online Access: | http://hdl.handle.net/1721.1/61216 |
| _version_ | 1826202342488276992 |
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| author | Antipov, Eugene |
| author2 | Alexander M. Klibanov. |
| author_facet | Alexander M. Klibanov. Antipov, Eugene |
| author_sort | Antipov, Eugene |
| collection | MIT |
| description | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2009. |
| first_indexed | 2024-09-23T12:05:57Z |
| format | Thesis |
| id | mit-1721.1/61216 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T12:05:57Z |
| publishDate | 2011 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/612162019-04-10T13:19:47Z Engineering a highly enantioselective horseradish peroxidase by directed evolution Engineering a highly enantioselective HRP by directed evolution Antipov, Eugene Alexander M. Klibanov. Massachusetts Institute of Technology. Dept. of Biological Engineering. Massachusetts Institute of Technology. Dept. of Biological Engineering. Biological Engineering. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2009. Cataloged from PDF version of thesis. Includes bibliographical references. There is an ever-growing demand for enantiopure chemical compounds, particularly new pharmaceuticals. Enzymes, as natural biocatalysts, possess many appealing properties as robust asymmetric catalysts for synthetic chemistry. However, their enantioselectivity toward most synthetically useful, non-natural substrates is typically low. Therefore, improving enzymatic enantioselectivity toward a given substrate is a practically important but arduous task. Here we report a highly efficient selection method for enhanced enzymatic enantioselectivity based on yeast surface display and fluorescenceactivated cell sorting (FACS). By exploiting the aforementioned method, in just three rounds of directed evolution we both greatly increased (up to 30-fold) and also reversed (up to 70-fold) the enantioselectivity of the commercially useful enzyme, horseradish peroxidase (HRP), toward a chiral phenol. In doing so, we discovered that mutations close to the active site not only preserve HRP catalytic activity but impact its enantioselectivity far greater than distal mutations. We thus examined how a single mutation near the active site (Argl78Glu) greatly enhances (by 25-fold) the enantioselectivity of yeast surface-bound HRP. Using kinetic analysis of enzymatic oxidation of various substrate analogs and molecular modeling of enzyme-substrate complexes, this enantioselectivity enhancement was attributed to changes in the transition state energy due to electrostatic repulsion between the carboxylates of the enzyme's Glu- 178 and the substrate's D enantiomer. In addition, the effect of yeast surface immobilization and influence of a fluorescent dye on controlling the enantioselectivity of the discovered HRP variants was investigated. Soluble variants were also shown to have marked improvements in enantioselectivity, which were rationalized by computational docking studies. by Eugene Antipov. Ph.D. 2011-02-23T14:30:54Z 2011-02-23T14:30:54Z 2009 2009 Thesis http://hdl.handle.net/1721.1/61216 701365609 eng MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 110 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Biological Engineering. Antipov, Eugene Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title | Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title_full | Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title_fullStr | Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title_full_unstemmed | Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title_short | Engineering a highly enantioselective horseradish peroxidase by directed evolution |
| title_sort | engineering a highly enantioselective horseradish peroxidase by directed evolution |
| topic | Biological Engineering. |
| url | http://hdl.handle.net/1721.1/61216 |
| work_keys_str_mv | AT antipoveugene engineeringahighlyenantioselectivehorseradishperoxidasebydirectedevolution AT antipoveugene engineeringahighlyenantioselectivehrpbydirectedevolution |