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Enantioselective biotransformations using engineered lipases from Candida antarctica
Stockholm University, Faculty of Science, Department of Organic Chemistry.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Enzymes are attractive catalysts in organic synthesis since they are efficient, selective and environmentally friendly. A large number of enzyme-catalyzed transformations have been described in the literature. If no natural enzyme can carry out a desirable reaction, one possibility is to modify an existing enzyme by protein engineering and thereby obtain a catalyst with the desired properties. In this thesis, the development of enantioselective enzymes and their use in synthetic applications is described. 

In the first part of this thesis, enantioselective variants of Candida antarctica lipase A (CALA) towards α-substituted p-nitrophenyl esters were developed by directed evolution. A highly selective variant of CALA towards p-nitrophenyl 2-phenylpropanoate was developed by pairwise randomization of amino acid residues close to the active site. The E value of this variant was 276 compared to 3 for the wild type.

An approach where nine residues were altered simultaneously was used to discover another highly enantioselective CALA variant (E = 100) towards an ibuprofen ester. The sterical demands of this substrate made it necessary to vary several residues at the same time in order to reach a variant with improved properties.

In the second part of the thesis, a designed variant of Candida antarctica lipase B (CALB) was employed in kinetic resolution (KR) and dynamic kinetic resolution (DKR) of secondary alcohols. The designed CALB variant (W104A) accepts larger substrates compared to the wild type, and by the application of CALB W104A, the scope of these resolutions was extended.

First, a DKR of phenylalkanols was developed using CALB W104A. An enzymatic resolution was combined with in situ racemization of the substrate, to yield the products in up to 97% ee. Secondly, the KR of diarylmethanols with CALB W104A was developed. By the use of diarylmethanols with two different aryl groups, highly enantioselective transformations were achieved.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University , 2012. , 55 p.
Keyword [en]
protein engineering, directed evolution, kinetic resolution, dynamic kinetic resolution, biotransformation, lipase
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-75000ISBN: 978-91-7447-468-8 (print)OAI: oai:DiVA.org:su-75000DiVA: diva2:513500
Public defence
2012-05-11, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows:  Paper 5: Submitted.

Available from: 2012-04-19 Created: 2012-04-02 Last updated: 2013-01-14Bibliographically approved
List of papers
1. Enantioselective Kinetic Resolution of p-Nitrophenyl 2-Phenylpropanoate by a Variant of Candida antarctica Lipase A Developed by Directed Evolution
Open this publication in new window or tab >>Enantioselective Kinetic Resolution of p-Nitrophenyl 2-Phenylpropanoate by a Variant of Candida antarctica Lipase A Developed by Directed Evolution
2010 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 20, 7038-7042 p.Article in journal (Refereed) Published
Abstract [en]

A variant of Candida antarctica lipase A (CalA) was developed for the hydrolysis of α-substituted p-nitrophenyl esters by directed evolution. The E values of this variant for 7 different esters was 45−276, which is a large improvement compared to 2−20 for the wild type. The broad substrate scope of this enzyme variant is of synthetic use, and hydrolysis of the tested substrates proceeded with an enantiomeric excess between 95−99%. A 30-fold increase in activity was also observed for most substrates. The developed enzyme variant shows (R)-selectivity, which is reversed compared to the wild type that is (S)-selective for most substrates.

Place, publisher, year, edition, pages
American Chemical Society, 2010
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-38337 (URN)10.1021/ja100593j (DOI)
Available from: 2010-04-08 Created: 2010-04-08 Last updated: 2017-12-12Bibliographically approved
2. Directed evolution of an enantioselective lipase with broad substrate scope for hydrolysis of α-substituted esters
Open this publication in new window or tab >>Directed evolution of an enantioselective lipase with broad substrate scope for hydrolysis of α-substituted esters
2010 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 20, 7038-7042 p.Article in journal (Refereed) Published
Abstract [en]

A variant of Candida antarctica lipase A (CalA) was developed for the hydrolysis of α-substituted p-nitrophenyl esters by directed evolution. The E values of this variant for 7 different esters was 45−276, which is a large improvement compared to 2−20 for the wild type. The broad substrate scope of this enzyme variant is of synthetic use, and hydrolysis of the tested substrates proceeded with an enantiomeric excess between 95−99%. A 30-fold increase in activity was also observed for most substrates. The developed enzyme variant shows (R)-selectivity, which is reversed compared to the wild type that is (S)-selective for most substrates.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-45970 (URN)10.1021/ja100593j (DOI)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2017-12-12Bibliographically approved
3. Combinatorial reshaping of the Candida antarctica lipase A substrate pocket for enantioselectivity using an extremely condensed library
Open this publication in new window or tab >>Combinatorial reshaping of the Candida antarctica lipase A substrate pocket for enantioselectivity using an extremely condensed library
Show others...
2012 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, no 1, 78-83 p.Article in journal (Refereed) Published
Abstract [en]

A highly combinatorial structure-based protein engineering method for obtaining enantioselectivity is reported that results in a thorough modification of the substrate binding pocket of Candida antarctica lipase A (CALA). Nine amino acid residues surrounding the entire pocket were simultaneously mutated, contributing to a reshaping of the substrate pocket to give increased enantioselectivity and activity for a sterically demanding substrate. This approach seems to be powerful for developing enantioselectivity when a complete reshaping of the active site is required. Screening toward ibuprofen ester 1, a substrate for which previously used methods had failed, gave variants with a significantly increased enantioselectivity and activity. Wild-type CALA has a moderate activity with an E value of only 3.4 toward this substrate. The best variant had an E value of 100 and it also displayed a high activity. The variation at each mutated position was highly reduced, comprising only the wild type and an alternative residue, preferably a smaller one with similar properties. These minimal binary variations allow for an extremely condensed protein library. With this highly combinatorial method synergistic effects are accounted for and the protein fitness landscape is explored efficiently.

Keyword
kinetic resolution, library design, protein design, enzyme catalysis
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-74997 (URN)10.1073/pnas.1111537108 (DOI)000298876500022 ()
Funder
Swedish Research Council, 621-2010-4737Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research
Available from: 2012-04-02 Created: 2012-04-02 Last updated: 2017-12-07Bibliographically approved
4. Mutated variant of Candida antarctica lipase B in (S)-selective dynamickinetic resolution of secondary alcohols
Open this publication in new window or tab >>Mutated variant of Candida antarctica lipase B in (S)-selective dynamickinetic resolution of secondary alcohols
Show others...
2011 (English)In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 1, 81-82 p.Article in journal (Refereed) Published
Abstract [en]

An (S)-selective dynamic kinetic resolution of secondaryalcohols, employing a mutated variant of Candida antarcticalipase B (CalB) gave products in 84–88% yield and in 90–97%ee.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:su:diva-59542 (URN)10.1039/c0ob00748j (DOI)000285157600011 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2011-07-05 Created: 2011-07-05 Last updated: 2017-12-11Bibliographically approved
5. Kinetic resolution of diarylmethanols using a mutated variant of lipase CALB
Open this publication in new window or tab >>Kinetic resolution of diarylmethanols using a mutated variant of lipase CALB
2012 (English)In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 68, no 37, 7613-7618 p.Article in journal (Refereed) Published
Abstract [en]

An enzymatic kinetic resolution of diarylmethanols via acylation has been developed. This was achieved by the use of a mutated variant of CALB that accepts larger substrates compared to the wild type. By the use of diarylmethanols with two differently sized aryl groups, enantioselective transformations were achieved. A larger size-difference led to a higher enantioselectivity. In addition, substrates with electronically different aryl groups, such as phenyl and pyridyl, also gave an enantioselective reaction. The highest E value was observed with a substrate where steric and electronic effects were combined.

Keyword
Kinetic resolution, Diarylmethanols, Biotransformation, Candida antarctica lipase B, Enzymatic resolution
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-81263 (URN)10.1016/j.tet.2012.06.040 (DOI)000307802300013 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

AuthorCount:4;

Available from: 2012-10-15 Created: 2012-10-15 Last updated: 2017-12-07Bibliographically approved

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