| 1. |
- Biundo, Antonino, et al.
(författare)
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Enzyme Modification
- 2021
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Ingår i: Biocatalysis for Practitioners. - : Wiley. ; , s. 33-62
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The chapter on protein engineering has introduced and discussed an overview of the available methods for the modification of enzymes. Starting with the classical directed evolution (DE) technique, which has been applied extensively throughout several different biocatalytic processes, the reader moves toward the semi-rational, rational, and de novo design of enzymes. Meanwhile, DE is clearly the current industry-leading technology; depending on the understanding of the particular enzymatic system, and on the available structural information, other techniques such as rational design are also becoming fast and efficient solutions for the development of new catalysts. This success would not be possible without the constant improvements of the computational techniques and the newly developed modeling systems for enzyme engineering.
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| 2. |
- Cho, I., et al.
(författare)
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Enantioselective Aminohydroxylation of Styrenyl Olefins Catalyzed by an Engineered Hemoprotein
- 2019
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 58:10, s. 3138-3142
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Tidskriftsartikel (refereegranskat)abstract
- Chiral 1,2-amino alcohols are widely represented in biologically active compounds from neurotransmitters to antivirals. While many synthetic methods have been developed for accessing amino alcohols, the direct aminohydroxylation of alkenes to unprotected, enantioenriched amino alcohols remains a challenge. Using directed evolution, we have engineered a hemoprotein biocatalyst based on a thermostable cytochrome c that directly transforms alkenes to amino alcohols with high enantioselectivity (up to 2500 TTN and 90 % ee) under anaerobic conditions with O-pivaloylhydroxylamine as an aminating reagent. The reaction is proposed to proceed via a reactive iron-nitrogen species generated in the enzyme active site, enabling tuning of the catalyst's activity and selectivity by protein engineering.
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| 3. |
- Dorau, Robin, et al.
(författare)
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Improved Enantioselectivity of Subtilisin Carlsberg Towards Secondary Alcohols by Protein Engineering
- 2018
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Ingår i: ChemBioChem (Print). - : Wiley. - 1439-4227 .- 1439-7633. ; 19:4, s. 338-346
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Tidskriftsartikel (refereegranskat)abstract
- Generally, the catalytic activity of subtilisin Carlsberg (SC) for transacylation reactions with secondary alcohols in organic solvent is low. Enzyme immobilization and protein engineering was performed to improve the enantioselectivity of SC towards secondary alcohols. Possible amino-acid residues for mutagenesis were found by combining available literature data with molecular modeling. SC variants were created by site-directed mutagenesis and were evaluated for a model transacylation reaction containing 1-phenylethanol in THF. Variants showing high E values (>100) were found. However, the conversions were still low. A second mutation was made, and both the E values and conversions were increased. Relative to that shown by the wild type, the most successful variant, G165L/M221F, showed increased conversion (up to 36 %), enantioselectivity (E values up to 400), substrate scope, and stability in THF.
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| 4. |
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| 5. |
- Gustafson, Karl P. J., et al.
(författare)
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Chemoenzymatic Dynamic Kinetic Resolution of Primary Benzylic Amines using Pd-0-CalB CLEA as a Biohybrid Catalyst
- 2019
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 25:39, s. 9174-9179
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we report on the use a biohybrid catalyst consisting of palladium nanoparticles immobilized on cross-linked enzyme aggregates of lipase B of Candida antarctica (CalB CLEA) for the dynamic kinetic resolution (DKR) of benzylic amines. A set of amines were demonstrated to undergo an efficient DKR and the recyclability of the catalysts was studied. Extensive efforts to further elucidate the structure of the catalyst are presented.
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| 6. |
- Görbe, Tamás, et al.
(författare)
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Design of a Pd(0)-CalB CLEA Biohybrid Catalyst and Its Application in a One-Pot Cascade Reaction
- 2017
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435 .- 2155-5435. ; 7:3, s. 1601-1605
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Tidskriftsartikel (refereegranskat)abstract
- Herein, a design of a biohybrid catalyst is described, consisting of Pd nanoparticles and a cross-linked network of aggregated lipase B enzyme of Candida antarctica (CalB CLEA) functioning as an active support for the Pd nanoparticles. Both entities of the hybrid catalyst showed good catalytic activity. The applicability was demonstrated in a one-pot reaction, where the Pd-catalyzed cycloisomerization of 4-pentynoic acid afforded a lactone that serves as an acyl donor in a subsequent selective enzymatic kinetic resolution of a set of sec-alcohols. The catalyst proved to be robust and could be recycled five times without a significant loss of activity.
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| 7. |
- Görbe, Tamás, et al.
(författare)
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Heterogeneous Acid-Catalyzed Racemization of Tertiary Alcohols
- 2018
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 24:1, s. 77-80
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Tidskriftsartikel (refereegranskat)abstract
- Tertiary alcohols are important structural motifs in natural products and building blocks in organic synthesis but only few methods are known for their enantioselective preparation. Chiral resolution is one of these approaches that leaves one enantiomer (50% of the material) unaffected. An attractive method to increase the efficiency of those resolutions is to racemize the unaffected enantiomer. In the present work, we have developed a practical racemization protocol for tertiary alcohols. Five different acidic resin materials were tested. The Dowex 50WX8 was the resin of choice since it was capable of racemizing tertiary alcohols without any byproduct formation. Suitable solvents and a biphasic system were investigated, and the optimized system was capable of racemizing differently substituted tertiary alcohols.
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| 8. |
- Görbe, Tamás, 1988-
(författare)
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Heterogeneous catalysis in racemization and kinetic resolution along a journey in protein engineering
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first part of my thesis concerns the use of heterogeneous acidic resins for racemization of tert-alcohols without any side-product formation. The focus was to develop a system which can be further extended to a DKR protocol consisting of an enzymatic KR reaction. Based on our knowledge of the resins, an unexpected migratory DKR protocol turned out to be an efficient method for the synthesis of carbocyclic allylic carbinols.The development of enzyme and metal catalyst hybrids was already an ongoing theme in our group. A supporter-free biohybrid catalyst was developed which can be used in several different types of reactions. The Pd(0)-CalB CLEA catalyst was applied in a two-step-cascade transformation and in the DKR of benzylic primary amines. The catalyst was characterized by different analytical techniques, to understand its composition and structure.The enzymes have always been the main focus of the studies and therefore wild type enzymes were initially utilized. However, these natural biocatalysts are associated with certain limitations. In contrast, protein engineering allows for enzymes to be modified and optimized. We have used the technique to create a subtilisin Carlsberg mutant, which was studied both by modeling and in vitro. The mutant was found to catalyze the (S)-selective transesterification of sec-alcohols containing long aliphatic carbon chains, and it also exhibited higher performance in organic solvent.The last project concerned the protein engineering of CalA enzyme towards tert-alcohols. The kinetic resolution of tert-alcohols with this enzyme is very slow but it occurs with good enantioselectivity. The aim was therefore to improve the activity of CalA via protein engineering. Seven amino acids were mutated close to the active site and a library was created based on our prediction. Throughout the screening, a few variants showed higher activity, which were sequenced and further analyzed in the transesterification of tert-alcohols.
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| 9. |
- Görbe, Tamas, et al.
(författare)
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Quantization and explicit diagonalization of new compactified trigonometric Ruijsenaars–Schneider systems
- 2018
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Ingår i: Journal of Integrable Systems. - : Oxford University Press (OUP). - 2058-5985. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Recently, Fehér and Kluck discovered, at the level of classical mechanics, new compactified trigonometric Ruijsenaars–Schneider n -particle systems, with phase space symplectomorphic to the (n−1) -dimensional complex projective space. In this article, we quantize the so-called type (i) instances of these systems and explicitly solve the joint eigenvalue problem for the corresponding quantum Hamiltonians by generalising previous results of van Diejen and Vinet. Specifically, the quantum Hamiltonians are realized as discrete difference operators acting in a finite-dimensional Hilbert space of complex-valued functions supported on a uniform lattice over the classical configuration space, and their joint eigenfunctions are constructed in terms of discretized An−1 Macdonald polynomials with unitary parameters.
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| 10. |
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