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  • 1.
    Cassimjee, Karim Engelmark
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Humble, Maria Svedendahl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Abedi, Vahak
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Chromobacterium violaceum omega-transaminase variant Trp60Cys shows increased specificity for (S)-1-phenylethylamine and 4 '-substituted acetophenones, and follows Swain-Lupton parameterisation2012Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 10, nr 28, s. 5466-5470Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For biocatalytic production of pharmaceutically important chiral amines the.-transaminase enzymes have proven useful. Engineering of these enzymes has to some extent been accomplished by rational design, but mostly by directed evolution. By use of a homology model a key point mutation in Chromobacterium violaceum omega-transaminase was found upon comparison with engineered variants from homologous enzymes. The variant Trp60Cys gave increased specificity for (S)-1-phenylethylamine (29-fold) and 4'-substituted acetophenones (similar to 5-fold). To further study the effect of the mutation the reaction rates were Swain-Lupton parameterised. On comparison with the wild type, reactions of the variant showed increased resonance dependence; this observation together with changed pH optimum and cofactor dependence suggests an altered reaction mechanism.

  • 2.
    Chen, Shan
    et al.
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Svedendahl Humble, Maria
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Stabilization of an amine transaminase for biocatalysis2016Inngår i: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 124, s. 20-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The amine transaminase from Chromobacterium violaceum (Cv-ATA) is a well-known enzyme to achievechiral amines of high enantiomeric excess in laboratory scales. However, the low operational stabilityof Cv-ATA limits the enzyme applicability on larger scales. In order to improve the operational stabilityof Cv-ATA, and thereby extending its applicability, factors (additives, co-solvents, organic solvents anddifferent temperatures) targeting enzyme stability and activity were explored in order to find out how tostore and apply the enzyme. The present investigation shows that the melting point of Cv-ATA is improvedby adding sucrose or glycerol, separately. Further, by storing the enzyme at higher concentrations and inco-solvents, such as; 50% glycerol, 20% methanol or 10% DMSO, the active dimeric structure of Cv-ATAis retained. Enzyme stored in 50% glycerol at −20◦C was e.g., still fully active after 6 months. Finally,the enzyme performance was improved 5-fold by a co-lyophilization with surfactants prior to usage inisooctane.

  • 3.
    Engelmark Cassimjee, Karim
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Svedendahl Humble, Maria
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Abedi, Vahak
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Chromobacterium violaceum ω-Transaminase VariantTrp60Cys Shows Increased Specificity for (S)-1-Phenylethylamine and 4’-Substituted Acetophenones, andFollows Swain-Lupton ParameterisationManuskript (preprint) (Annet vitenskapelig)
  • 4.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi. KTH Royal Institute of Technology.
    Amine Transaminases in Biocatalytic Amine Synthesis2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The use of enzymes, nature´s own catalysts, both isolated or as whole cells to perform chemical transformations is called biocatalysis. As a complement to classical chemical catalysis, biocatalysis can be an environmentally friendly and more economical option in the production and synthesis of chemicals. Research on the application of amine transaminases in synthesis of chiral amines have exploded over the last two decades and interest from the industry is increasing. Amine transaminases are promising catalysts due to their ability to perform reductive amination of ketones with excellent enantioselectivity.

    For a process to be efficient, high substrate specificity of the applied enzyme is an important factor. A variant of Chromobacterium violaceum amine transaminase that was obtained through rational design has an increased specific activity toward (S)-1-phenylethylamine and a set of 4´-substituted acetophenones. This result makes this variant a promising catalyst for the asymmetric synthesis of similar amines.

    Amine transaminase catalyzed asymmetric synthesis of amines generally suffers from unfavorable equilibrium. Two methods that include spontaneous tautomerization and biocatalytic amidation for equilibrium displacement have therefore been developed.

    Efficient assays and screening methods are demanded for the discovery and development of novel amine transaminases. For this purpose, a sensitive fluorescence-based assay that holds promise as a high-throughput screening method was developed.

    One of the major obstacles for application of enzymes in industrial processes is the instability of the enzyme toward harsh conditions. The stability of Chromobacterium violaceum amine transaminase was investigated and improved using co-solvents and other additives. Co-lyophilization with surfactants was also applied to improve the performance of the same enzyme in organic solvents.

  • 5.
    Land, Henrik
    et al.
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Hendil-Forssell, Peter
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Martinelle, Mats
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    One-pot biocatalytic amine transaminase/acyl transferase cascade for aqueous formation of amides from aldehydes or ketones2016Inngår i: catalysis science & technology, ISSN 2044-4753, Vol. 6, s. 2897-2900Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient one-pot one-step biocatalytic amine transaminase/acyl transferase cascade for the formation of amides from the corresponding aldehydes and ketones in aqueous solution has been developed. N-benzyl-2-methoxyacetamide has been synthesized utlilizing the developed cascade in conversions up to 97%. The cascade was also evaluated for the synthesis of chiral amides.

  • 6. Scheidt, Thomas
    et al.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Anderson, Mattias
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Chen, Yujie
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Yi, Dong
    Fessner, Wolf-Dieter
    Fluorescence-Based Kinetic Assay for High-Throughput Discovery and Engineering of Stereoselective omega-Transaminases2015Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 357, nr 8, s. 1721-1731Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    omega-Transaminases are a valuable class of enzymes for the production of chiral amines with either (R)- or (S)-configuration in high optical purity and 100% yield by the biocatalytic reductive amination of prochiral ketones. A versatile new assay was developed to quantify omega-transaminase activity for the kinetic characterization and enantioselectivity typing of novel or engineered enzymes based on the conversion of 1-(6-methoxynaphth-2-yl)alkylamines. The associated release of the acetonaphthone product can be monitored by the development of its bright fluorescence at 450 nm with very high sensitivity and selectivity. The assay principle can be used to quantify omega-transaminase catalysis over a very broad range of enzyme activity. Because of its simplicity and low substrate consumption in microtiter plate format the assay seems suitable for liquid screening campaigns with large library sizes in the directed evolution of optimized transaminases. For assay substrates that incorporate structural variations, an efficient modular synthetic route was developed. This includes racemate resolution by lipase-catalyzed transacylation to furnish enantiomerically pure (R)and (S)-configured amines. The latter are instrumental for the rapid enantioselectivity typing of omega-transaminases. This method was used to characterize two novel (S)-selective taurine-pyruvate transaminases of the subtype 6a from thermophilic Geobacillus thermodenitrificans and G. thermoleovorans.

  • 7. Steffen-Munsberg, F.
    et al.
    Vickers, C.
    Thontowi, A.
    Schätzle, S.
    Meinhardt, T.
    Svedendahl Humble, M.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Bornscheuer, U. T.
    Höhne, M.
    Revealing the Structural Basis of Promiscuous Amine Transaminase Activity2013Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, nr 1, s. 154-157Artikkel i tidsskrift (Fagfellevurdert)
  • 8. Steffen-Munsberg, F.
    et al.
    Vickers, C.
    Thontowi, A.
    Schätzle, S.
    Tumlirsch, T.
    Svedendahl Humble, M.
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Bornscheuer, U. T.
    Höhne, M.
    Connecting Unexplored Protein Crystal Structures to Enzymatic Function2013Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, nr 1, s. 150-153Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Steffen-Munsberg, Fabian
    et al.
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi. Greifswald University, Germany.
    Vickers, Clare
    Kohls, Hannes
    Land, Henrik
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Mallin, Hendrik
    Nobili, Alberto
    Skalden, Lilly
    van den Bergh, Tom
    Joosten, Henk-Jan
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Höhne, Matthias
    Bornscheuer, Uwe T.
    Bioinformatic analysis of a PLP-dependent enzyme superfamily suitable for biocatalytic applications2015Inngår i: Biotechnology Advances, ISSN 0734-9750, E-ISSN 1873-1899, Vol. 33, nr 5, s. 566-604Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this review we analyse structure/sequence-function relationships for the superfamily of PLP-dependent enzymes with special emphasis on class III transaminases. Amine transaminases are highly important for applications in biocatalysis in the synthesis of chiral amines. In addition, other enzyme activities such as racemases or decarboxylases are also discussed. The substrate scope and the ability to accept chemically different types of substrates are shown to be reflected in conserved patterns of amino acids around the active site. These findings are condensed in a sequence-function matrix, which facilitates annotation and identification of biocatalytically relevant enzymes and protein engineering thereof.

  • 10.
    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.

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