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Influence of delta-functional groups on the enantiorecognition of secondary alcohols by Candida antarctica lipase B
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
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2008 (English)In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, no 12, 1968-1974 p.Article in journal (Refereed) Published
Abstract [en]

The selectivity of acetylation of delta-functionalized secondary alcohols catalyzed by Candida antarctica lipase B has been examined by molecular dynamics. The results from the simulation show that a delta-alcohol functionality forms a hydrogen bond with the carbonyl group of Thr 40. This interaction stabilizes the tetrahedral intermediate and thus leads to selective acetylation of the R enantiomer. A stabilizing interaction of the delta-(R)-acetoxy group with the peptide NH of alanine 282 was also observed. No stabilizing interaction could be found for the delta-keto functionality, and it is proposed that this is the reason for the experimentally observed decrease in enantioselectivity. From these results, it was hypothesized that the enantioselectivity could be restored by mutating the alanine in position 281 for serine. The mutation was made experimentally, and the results show that the E value increased from 9 to 120.

Place, publisher, year, edition, pages
2008. Vol. 9, no 12, 1968-1974 p.
URN: urn:nbn:se:su:diva-14702DOI: doi:10.1002/cbic.200800036ISI: 000258586600018OAI: diva2:181222
Available from: 2009-01-02 Created: 2009-01-02 Last updated: 2010-04-09Bibliographically approved
In thesis
1. Theoretical modeling of metal- and enzyme catalyzed transformations
Open this publication in new window or tab >>Theoretical modeling of metal- and enzyme catalyzed transformations
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on describing and predicting catalytic reactions. The major part of the work is based on density functional theory (DFT). In some cases where the size of the investigated system precluded the use of more accurate methods molecular dynamics was employed. In several cases the proposed mechanism was later tested in the laboratory. A few examples where the predictions were confirmed are:

  • The formation of an acyl intermediate in the activation of a ruthenium catalyst used for racemizing alcohols. This intermediate was observed by both NMR and in situ FT-IR.
  • The improvement of the substrate specificity and catalytic activity of Candida antarctica lipase A by modifying amino acids close to the active site.
  • The improved specificity of Candida antarctica lipase B toward δ-substituted secondary alcohols by an enzyme variant where the alanine in position 281 was exchanged for a serine.

In other cases experimental results were complemented with a theoretical investigation, for example:

  • The observed second order rate constant for a ruthenium based catalyst used for water oxidation was explained and a novel intramolecular mechanism based on a high valent ruthenium dimer was suggested.
  • The effects of electron withdrawing/donating axial ligands on the performance of ruthenium catalyzed water oxidation were addressed.
  • Mechanisms of H2 activation by Lewis acid/Lewis base adducts were rationalized. One example of the predictive power of computational chemistry is the mechanism of hydrogen uptake by phosphanylboranes; the potential energy barrier for the transition state could be predicted within a few kcal/mol based on the orbital energies of the starting material.
Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2010. 96 p.
density functinal theory, computational chemistry, directed evolution, enzyme, mechanistic studies, catalysis, ruthenium, hydrogen transfer, racemization, artificial photosynthesis, frustrated lewis pairs, hydrogen storage
National Category
Organic Chemistry
Research subject
Organic Chemistry
urn:nbn:se:su:diva-38344 (URN)978-91-7447-063-5 (ISBN)
Public defence
2010-05-12, Magnelisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 8: In press.Available from: 2010-04-20 Created: 2010-04-08 Last updated: 2010-05-28Bibliographically approved

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