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  • 101.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Branneby, Cecilia
    Lindberg, Lina
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Reversed Enantiopreference of an omega-Transaminase by a Single-Point Mutation2010Inngår i: CHEMCATCHEM, ISSN 1867-3880, Vol. 2, nr 8, s. 976-980Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Altering the characteristics of an active-site loop in an (S)-selective omega-transaminase from Arthrobacter citreus (variant CNB05-01) influences the enantioselectivity. This active-site loop belongs to the second subunit of the dimeric enzyme structure that participates in the coordination of pyridoxal-5'-phosphate (PLP) in the so called "phosphate group binding cup". Three amino acid residues (E326, V328, and Y331) in this loop are selected by homology modeling for site-directed mutagenesis aiming to increase the enzyme enantioselectivity for 4-fluorophenylacetone. By combining these mutations, five enzyme variants are created. The performance of these variants is explored using a model system consisting of isopropylamine and 4-fluorophenylacetone or 4-nitroacetophenone in asymmetric synthesis using a whole-cell system approach. Three of the five variants show increased enantioselectivity for 4-fluorophenylacetone compared to CNB05-01. Variant CNB05-01/Y331C increases the enantioselectivity from 98% ee to over 99.5% ee. A single-point mutation, V328A, turn the (S)-selective omega-transaminase into an (R)-selective enzyme. This switch in enantioselectivity is substrate dependent, exhibiting (R) selectivity for 4-fluorophenylacetone and retaining (S) selectivity for 4-nitroacetophenone. The shift in enantiopreference is further confirmed by molecular docking simulations. Homology modeling is shown to be a powerful tool to target important amino acid residues in this enzyme in order to improve enantioselectivity by rational design.

  • 102.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Branneby, Cecilia
    Lindberg, Lina
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Reversed enantiopreference of an ω-transaminase by a single-point mutationManuskript (preprint) (Annet vitenskapelig)
  • 103.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Carlqvist, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Branneby, Cecilia
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Allnér, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Frise, Anton
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    Direct Epoxidation in Candida antarctica Lipase B Studied by Experiment and Theory2008Inngår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, nr 15, s. 2443-2451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Candida antarctica lipase B (CALB) is a promiscuous serine hydrolase that, besides its native function, catalyzes different side reactions, such as direct epoxidation. A single-point mutant of CALB demonstrated a direct epoxidation reaction mechanism for the epoxidation of alpha,beta-unsaturated aldehydes by hydrogen peroxide in aqueous and organic solution. Mutation of the catalytically active Ser105 to alanine made the previously assumed indirect epoxidation reaction mechanism impossible. Gibbs free energies, activation parameters, and substrate selectivities were determined both computationally and experimentally. The energetics and mechanism for the direct epoxidation in CALB Ser105Ala were investigated that the reaction proceeds through a two step-mechanism with formation of an oxyanionic intermediate. The active-site residue His224 functions as a general acid-base catalyst with support from Asp187. Oxyanion stabilization is facilitated by two hydrogen bonds from Thr40.

  • 104.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Engelmark Cassimjee, Karim
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Abedi, Vahak
    AstraZeneca.
    Federsel, Hans-Jürgen
    AstraZeneca.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    From S to R: Key Residues Controlling Enantiomer Preference and Activity in omega-Transaminase2011Konferansepaper (Fagfellevurdert)
  • 105.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Engelmark Cassimjee, Karim
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Branneby, C.
    Abedi, V.
    Wells, A.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    CASCAT: Redesign of omega-Transaminases for Synthesis of Chiral Amines2010Inngår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 150, s. S123-S124Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Transaminases (EC 2.6.1.18) are attractive biocatalysts for synthesis of chiral amines and alpha-amino acids. These enzymes catalyze transfer of an amine group from a donor substrate to an acceptor compound using the cofactor pyridoxal-5′-phoshate (PLP). omega-Transaminases are a versatile subgroup of the transaminases that does not require a carboxylic acid group in alpha-position (in contradiction toalpha-transaminases) and hence accept a wider spectrum of ketones or amines. The omega-transaminases are employed industrially for production of both R- and S-enantiopure amines.

    One bottleneck is the unfavourable equilibrium in such reactions run in the synthesis mode. We have developed a one-pot multi-enzyme system in a cascade fashion for equilibrium displacement by removing formed acetone.

    Another issue is the fact that most omega-transaminases show S-selectivity, however a few R-selective strains do exist. We have used an S-selective omega-transaminase variant from Arthrobacter citreus and created an R-selective variant by rational redesign using a homology enzyme model. This homology modelling/rational design approach was further explored on an omega-transaminase from Chromobacterium violaceum.

  • 106.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Engelmark Cassimjee, Karim
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Sjöstrand, Ulf
    Cambrex Karlskoga AB.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Rational Redesign of ω-Transaminases2010Konferansepaper (Fagfellevurdert)
  • 107.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Exploring Promiscuous Activities in a Lipase2009Konferansepaper (Fagfellevurdert)
  • 108.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Fast carbon-carbon bond formation by a promiscuous lipase2005Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, nr 51, s. 17988-17989Artikkel i tidsskrift (Fagfellevurdert)
  • 109.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Catalytic Promiscuity of a Lipase for Direct Epoxidation Reactions2007Inngår i: / [ed] Vicente Gotor, 2007Konferansepaper (Fagfellevurdert)
  • 110.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Promiscuous Reactions in Candida antarctica lipase B2008Konferansepaper (Fagfellevurdert)
  • 111.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Jovanovic, Biljana
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    A Non-Hydrolytic Lipase Mutant with Michael Addition Activity for Esters in Water2008Inngår i: Biocat2008 / [ed] Ralf Grote, Garabed Antranikian, 2008Konferansepaper (Fagfellevurdert)
  • 112.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Jovanovic, Biljana
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Fransson, Linda
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Suppressed Native Hydrolytic Activity of a Lipase to Reveal Promiscuous Michael Addition Activity in Water2009Inngår i: CHEMCATCHEM, ISSN 1867-3880, Vol. 1, nr 2, s. 252-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Suppression of,the,native hydrolytic activity of Pseudozyma antarctica lipase B (PalB) (formerly Candida antarctica lipase B) in water is demonstrated. By replacing the catalytic Ser 105 residue with an alanine unit, promiscuous Michael addition activity is favored. A Michael addition reaction between methyl acrylate and acetylacetone was explored as a model system. For the PalB Ser 105 Ala mutant, the hydrolytic activity was suppressed more than 1000 times and at the same time, the Michael addition activity was increased by a factor of 100. Docking studies and molecular dynamics simulations revealed an increased ability of the PalB Ser 105 Ala mutant to harbor the substrates close to a catalytically competent conformation.

  • 113.
    Vongvilai, Pornrapee
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Linder, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Sakulsombat, Morakot
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Humble, Maria Svedendahl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Racemase Activity of B. cepacia Lipase Leads to Dual-Function Asymmetric Dynamic Kinetic Resolution of alpha-Aminonitriles2011Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, nr 29, s. 6592-6595Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Applaudable promiscuity: Racemase-type activity discovered for B. cepacia lipase with N-substituted α-aminonitriles is proposed to involve a C-C bond-breaking/forming mechanism in the hydrolase site of the enzyme, as supported by experimental data and calculations. This promiscuous activity in combination with the transacylation activity of the enzyme enabled the asymmetric synthesis of N-methyl α-aminonitrile amides in high yield (see scheme).

  • 114.
    Wang, Bo
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    An efficient single-enzymatic cascade for asymmetric synthesis of chiral amines catalyzed by omega-transaminase2013Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, nr 2, s. 161-163Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient single-enzymatic cascade approach for the asymmetric synthesis of chiral amines has been developed, which applies the amino donor 3-aminocyclohexa-1,5-dienecarboxylic acid spontaneously tautomerizing to reach reaction completion with excellent ee values.

123 101 - 114 of 114
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