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  • 1.
    Berglund, Per
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Svedendahl, Maria
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Abedi, Vahak
    AstraZeneca.
    Wells, Andrew
    AstraZeneca.
    Federsel, Hans-Jürgen
    AstraZeneca.
    Omega-Transaminases Redesigned for Chiral Amine Synthesis2011In: BIT Life Sciences’ 2nd Symposium on Enzymes & Biocatalysis, Dalian, China: BIT Life Sciences , 2011Conference paper (Refereed)
  • 2.
    Cassimjee, Karim Engelmark
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Humble, Maria Svedendahl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Land, Henrik
    KTH, School of Biotechnology (BIO), Biochemistry.
    Abedi, Vahak
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Chromobacterium violaceum omega-transaminase variant Trp60Cys shows increased specificity for (S)-1-phenylethylamine and 4 '-substituted acetophenones, and follows Swain-Lupton parameterisation2012In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 10, no 28, p. 5466-5470Article in journal (Refereed)
    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.

  • 3.
    Cassimjee, Karim Engelmark
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Humble, Maria Svedendahl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Miceli, Valentina
    KTH, School of Biotechnology (BIO), Biochemistry.
    Colomina, Carla Granados
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Active Site Quantification of an omega-Transaminase by Performing a Half Transamination Reaction2011In: ACS CATAL, ISSN 2155-5435, Vol. 1, no 9, p. 1051-1055Article in journal (Refereed)
    Abstract [en]

    Measurement of the active enzyme fraction in a given enzyme preparation is a requirement for accurate kinetic measurements and activity comparisons of, for example, engineered mutants. omega-Transaminases, enzymes capable of interconverting ketones and amines by use of pyridoxal-5'-phosphate (PIP), can be used for the production of pharmaceutically important chiral amines but are subject to engineering to meet the practical requirements in synthesis reactions. Therefore, an active site quantification method is needed. Such a method was developed by quantifying the amount of consumed substrate in a virtually irreversible half transamination reaction. (S)-1-phenylethylamine was converted to acetophenone, while the holo enzyme (E-PLP) was converted to apo enzyme with bound pyridoxamine-5'-phosphate (E:PMP). Further, the mass of active enzyme was correlated to the absorbance of the holo enzyme to achieve a direct measurement method. The active Chromobacterium violaceum omega-transaminase with bound PLP can be quantified at 395 nm with an apparent extinction coefficient of 8.1 mM(-1) cm(-1).

  • 4.
    Cassimjee, Karim Engelmark
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Kourist, Robert
    Lindberg, Diana
    Larsen, Marianne Wittrup
    KTH, School of Biotechnology (BIO), Biochemistry.
    Thanh, Nguyen Hong
    KTH, School of Biotechnology (BIO), Biochemistry.
    Widersten, Mikael
    Bornscheuer, Uwe T.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    One-step enzyme extraction and immobilization for biocatalysis applications2011In: Biotechnology Journal, ISSN 1860-6768, E-ISSN 1860-7314, Vol. 6, no 4, p. 463-469Article in journal (Refereed)
    Abstract [en]

    An extraction/immobilization method for His(6)-tagged enzymes for use in synthesis applications is presented. By modifying silica oxide beads to be able to accommodate metal ions, the enzyme was tethered to the beads after adsorption of Co(II). The beads were successfully used for direct extraction of C. antarctica lipase B (CalB) from a periplasmic preparation with a minimum of 58% activity yield, creating a quick one-step extraction-immobilization protocol. This method, named HisSi Immobilization, was evaluated with five different enzymes [Candida antarctica lipase B (CalB), Bacillus subtilis lipase A (BslA), Bacillus subtilis esterase (BS2), Pseudomonas fluorescence esterase (PFE), and Solanum tuberosum epoxide hydrolase 1 (StEH1)]. Immobilized CalB was effectively employed in organic solvent (cyclohexane and acetonitrile) in a transacylation reaction and in aqueous buffer for ester hydrolysis. For the remaining enzymes some activity in organic solvent could be shown, whereas the non-immobilized enzymes were found inactive. The protocol presented in this work provides a facile immobilization method by utilization of the common His 6 tag, offering specific and defined means of binding a protein in a specific location, which is applicable for a wide range of enzymes.

  • 5.
    Cassimjee, Karim Engelmark
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Trummer, Martin
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Silica-immobilized His(6)-tagged enzyme: Alanine racemase in hydrophobic solvent2008In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 99, no 3, p. 712-716Article in journal (Refereed)
    Abstract [en]

    A new immobilization method for enzymes is presented to facilitate synthetic applications in aqueous as well as organic media. The enzyme Alanine racemase (AlaR) from Geobacillus stearothermophilus was cloned, overexpressed and then immobilized on a silica-coated thin-layer chromatography plate to create an enzyme surface. The enzyme, fused to a His(6)-tag at its N-terminal, was tethered to the chemically modified silica-coated TLC plate through cobalt ions. The immobilized enzyme showed unaltered kinetic parameters in small-scale stirred reactions and retained its activity after rinsing, drying, freezing or immersion in n-hexane. This practical method is a first step towards a general immobilization method for synthesis applications with any enzyme suitable for His(6)-tagging.

  • 6.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Tools in biocatalysis: enzyme immobilisation on silica and synthesis of enantiopure amines2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents two techniques in the field of biocatalysis:

    An enzyme immobilisation method based on the His6-tag for attachment on modified silica oxide beads, and it’s employment in aqueous and organic medium for synthesis applications. The method functions as a one step extraction and immobilisation protocol.

    An equilibrium displacement system which enables complete conversion in reactions with ω-transaminases where isopropylamine is the donor, a route for synthesis of pharmaceutically interesting enantiopure amines.

    Biocatalysis is predicted to be a paramount technology for an environmentally sustainable chemical industry, to which every newly developed method represents a small but important step. The work done here is aimed to be a part of this development.

     

  • 7.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    ω-Transaminase in Biocatalysis: Methods, Reactions and Engineering2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biocatalysis offers an alternative to classic chemistry by using enzymes, the protein catalysts of Nature, for production of fine chemicals. Evolution has created enzymes capable of catalysis at moderate temperature of a specific reaction in the presence of a plethora of compounds in the aqueous cell environment. The focal point of biocatalysis is to utilise these traits in vitro, for creation of valuable molecules.

    The ω-transaminase is an enzyme capable of producing chiral amines, compounds used to great extent in pharmaceuticals. Much effort has in recent years been invested in the research and engineering of this enzyme type since the catalysed reaction offers an advantageous alternative to classical techniques. Nevertheless, there is a need for method development, adaptation of the enzyme and increased understanding of the catalytic mechanism for feasibility as an effective biocatalyst for unnatural substrates. This thesis addresses a chosen set of obstacles as a contribution to meeting the demands at hand. ω-Transaminase from Chromobacterium violaceum and Arthrobacter citreus was used.

    Many homologous ω-transaminases are available, which are also subject to engineering where variants are produced. To accurately compare their kinetic constants an active site quantification method is required but has not been available. Here such a method is presented (Paper 1) which encompasses a virtually irreversible half transamination reaction.

    In stereoselective synthesis the ω-transaminase catalysed equilibrium reaction inherently results in incomplete conversion. An equilibrium displacement system is presented (Paper II) where isopropylamine is the amino donor for transamination of acetophenone and derivatives thereof, coupled to an enzymatic cascade reaction.

    For many unnatural substrates the specificity and enantiospecificity is insufficient. Rationally redesigned variants were produced with improved properties for chosen substrates (Paper III and IV). The catalytic contributions of field and resonance of a variant compared to the wild type were investigated (Paper IV) for increased knowledge of the mechanism.

    For rational redesign of an enzyme the three-dimensional structure is required, of which only a few are available for the ω-transaminases. X-ray crystallographic structures of the holo and apo form of Chromobacterium violaceum ω-transaminase were made (Paper V) which revealed significant structural rearrangements upon coenzyme binding which may be of consequence for future engineering.

  • 8.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Affinity Tag Purification Method and Immobilization of the Promiscuous Enzyme Alanine Racemase2006Conference paper (Refereed)
  • 9.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Affinity Tag Purification Method of the Promiscuous Enzyme Alanine Racemase2006In: Book of abstracts, 2006Conference paper (Other academic)
  • 10.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Immobilization Method for the Promiscuous Enzyme Alanine Racemase2007In: BIOTRANS Oviedo 2007 / [ed] Vicente Gotor, 2007Conference paper (Refereed)
  • 11.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    Abedi, Vahak
    Wells, Andrew
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Transaminations with isopropyl amine: equilibrium displacement with yeast alcohol dehydrogenase coupled to in situ cofactor regeneration2010In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, no 30, p. 5569-5571Article in journal (Refereed)
    Abstract [en]

    Enantiopure chiral amines synthesis using omega-transaminases is hindered by an unfavourable equilibrium, but when using isopropylamine as the amine donor the equilibrium can be completely displaced by using a specific dehydrogenase in situ for removal of formed acetone.

  • 12.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Sjöstrand, Ulf
    Cambrex Karlskoga AB.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    High Yield Transamination with Isopropyl Amine as Donor, by Employment of YADH and in situ Cofactor Regeneration2009Conference paper (Refereed)
  • 13.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Sjöstrand, Ulf
    Cambrex Karlskoga AB.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    High Yield Transamination with Isopropyl Amine as Donor, by Employment of YADH and in situ Cofactor Regeneration2009In: Book of abstracts, 2009Conference paper (Refereed)
  • 14.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Kourist, Robert
    University of Greifswald, Germany.
    Lindberg, Diana
    Uppsala university, SE.
    Wittrup Larsen, Marianne
    KTH, School of Biotechnology (BIO), Biochemistry.
    Widersten, Mikael
    Uppsala university, SE.
    Bornscheuer, Uwe T
    University of Greifswald, DE.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    A One Step Enzyme Extraction and Immobilization Method for Organic and Aqueous Solvents2008In: Biocat2008 / [ed] Ralf Grote, Garabed Antranikian, Hamburg, Germany: TuTech Innovation GmbH , 2008Conference paper (Refereed)
  • 15.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Kourist, Robert
    University of Greifswald, Germany.
    Lindberg, Diana
    Uppsala university, SE.
    Wittrup Larsen, Marianne
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Widersten, Mikael
    Uppsala university, SE.
    Bornscheuer, Uwe T
    University of Greifswald, DE.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    A One Step General Enzyme Immobilization Method for Organic and Aqueous Solvents2008In: Book of Abstracts, 2008Conference paper (Refereed)
  • 16.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Marí­n, Sílvia Rodríguez
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Synthesis of cyclic polyamines by enzymatic generation of an amino aldehyde in situ2012In: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 33, no 18, p. 1580-1583Article in journal (Refereed)
    Abstract [en]

    Multifunctional polycationic polyamines, for example, used in drug and gene delivery, have product range limitations in their synthesis methods. Here, we synthesize a polyamine by forming a self-assembling amino aldehyde from the corresponding amino alcohol with horse liver alcohol dehydrogenase (HLADH), followed by reduction. Circular polyamines were synthesized from 3-amino-propan-1-ol as starting material, analogous to cyclic polyamines formed from azetidin. The product had an isolated yield of 89.7% or 15.3 g L -1. The predicted range of possible polyamine products by this method is broad since many amino alcohols are putative substrates for HLADH. The enzyme also had activity for 2-amino-propan-1-ol and 2-amino-2-phenyl-ethanol, for which the enantioselectivity was 330 (S) and 32 (R), respectively.

  • 17.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Svedendahl Humble, Maria
    KTH, School of Biotechnology (BIO), Biochemistry.
    Land, Henrik
    KTH, School of Biotechnology (BIO), Biochemistry.
    Abedi, Vahak
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Chromobacterium violaceum ω-Transaminase VariantTrp60Cys Shows Increased Specificity for (S)-1-Phenylethylamine and 4’-Substituted Acetophenones, andFollows Swain-Lupton ParameterisationManuscript (preprint) (Other academic)
  • 18.
    Engelmark Cassimjee, Karim
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Svedendahl, Maria
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Rational Redesign of omega-Transaminase2010In: Biocat2010, Hamburg, Germany: TuTech Verlag , 2010Conference paper (Refereed)
  • 19. Gaffney, Darragh
    et al.
    Abdallah, Noreldeen H.
    Cooney, Jakki C.
    Laffir, Fathima R.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Hanefeld, Ulf
    Magner, Edmond
    Preparation and characterisation of a Ni2+/Co2+-cyclam modified mesoporous cellular foam for the specific immobilisation of His(6)-alanine racemase2014In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 109, p. 154-160Article in journal (Refereed)
    Abstract [en]

    Nickel and cobalt cyclam modified mesocellular foam (MCF) materials were prepared and characterised. The metal cyclam modified materials displayed reduced surface areas and pore diameters in comparison to MCF. The modified materials were used to specifically anchor a histidine tagged form of the enzyme, alanine racemase (HT-AlaR). Non-specific adsorption was predominantly hydrophobic//hydrophilic in nature and could be significantly reduced in the presence of 2% polyethylene glycol. The activity of HT-AlaR immobilised on Ni and Co-MCF was essentially the same as that of the free enzyme, demonstrating that enzymes can be specifically immobilised within the pores of mesoporous materials in a stable and catalytically active manner.

  • 20. Hauer, Bernhard
    et al.
    Engelmark Cassimjee, David Karim
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Process for producing polyamines2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a process for the production of a polyamine involving the use of enzymes; in particular to a process performed in aqueous environment; to the polyamines produced by said method; as well as the use of said polyamines for manufacturing paper, for immobilizing enzymes, or for preparing pharmaceutical or cosmetical compositions. The invention also relates to a novel method for in situ regeneration of cofactors NAD(P)+.

  • 21.
    Svedendahl Humble, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Abedu, Vahak
    Federsel, Hans-Jürgen
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Key Amino Acid Residues for Reversed or Improved Enantiospecificity of an omega-Transaminase2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 8, p. 1167-1172Article in journal (Refereed)
    Abstract [en]

    Transaminases inherently possess high enantiospecificity and are valuable tools for stereoselective synthesis of chiral amines in high yield from a ketone and a simple amino donor such as 2-propylamine. Most known ?-transaminases are (S)-selective and there is, therefore, a need of (R)-selective enzymes. We report the successful rational design of an (S)-selective ?-transaminase for reversed and improved enantioselectivity. Previously, engineering performed on this enzyme group was mainly based on directed evolution, with few exceptions. One reason for this is the current lack of 3D structures. We have explored the ?-transaminase from Chromobacterium violaceum and have used a homology modeling/rational design approach to create enzyme variants for which the activity was increased and the enantioselectivity reversed. This work led to the identification of key amino acid residues that control the activity and enantiomeric preference. To increase the enantiospecificity of the C. violaceum ?-transaminase, a possible single point mutation (W60C) in the active site was identified by homology modeling. By site-directed mutagenesis this enzyme variant was created and it displayed an E value improved up to 15-fold. In addition, to reverse the enantiomeric preference of the enzyme, two other point mutations (F88A/A231F) were identified. This double mutation created an enzyme variant, which displayed substrate dependent reversed enantiomeric preference with an E value shifted from 3.9 (S) to 63 (R) for 2-aminotetralin.

  • 22.
    Svedendahl Humble, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Håkansson, Maria
    Kimbung, Yengo R
    Walse, Björn
    Abedi, Vahak
    Federsel, Hans-Jürgen
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Logan, Derek T
    Crystal structures of the Chromobacterium violaceumω-transaminase reveal major structural rearrangements upon binding of coenzyme PLP.2012In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 279, no 5, p. 779-792Article in journal (Refereed)
    Abstract [en]

    The bacterial ω-transaminase from Chromobacterium violaceum (Cv-ωTA, EC2.6.1.18) catalyses industrially important transamination reactions by use of the coenzyme pyridoxal 5'-phosphate (PLP). Here, we present four crystal structures of Cv-ωTA: two in the apo form, one in the holo form and one in an intermediate state, at resolutions between 1.35 and 2.4 Å. The enzyme is a homodimer with a molecular mass of ∼ 100 kDa. Each monomer has an active site at the dimeric interface that involves amino acid residues from both subunits. The apo-Cv-ωTA structure reveals unique 'relaxed' conformations of three critical loops involved in structuring the active site that have not previously been seen in a transaminase. Analysis of the four crystal structures reveals major structural rearrangements involving elements of the large and small domains of both monomers that reorganize the active site in the presence of PLP. The conformational change appears to be triggered by binding of the phosphate group of PLP. Furthermore, one of the apo structures shows a disordered 'roof ' over the PLP-binding site, whereas in the other apo form and the holo form the 'roof' is ordered. Comparison with other known transaminase crystal structures suggests that ordering of the 'roof' structure may be associated with substrate binding in Cv-ωTA and some other transaminases. DATABASE: The atomic coordinates and structure factors for the Chromobacterium violaceumω-transaminase crystal structures can be found in the RCSB Protein Data Bank (http://www.rcsb.org) under the accession codes 4A6U for the holoenzyme, 4A6R for the apo1 form, 4A6T for the apo2 form and 4A72 for the mixed form STRUCTURED DIGITAL ABSTRACT: •  -transaminases and -transaminases bind by dynamic light scattering (View interaction) •  -transaminase and -transaminase bind by x-ray crystallography (View interaction) •  -transaminase and -transaminase bind by x-ray crystallography (View interaction).

  • 23.
    Svedendahl, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Abedi, Vahak
    AstraZeneca.
    Federsel, Hans-Jürgen
    AstraZeneca.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    From S to R: Key Residues Controlling Enantiomer Preference and Activity in omega-Transaminase2011Conference paper (Refereed)
  • 24.
    Svedendahl, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Branneby, C.
    Abedi, V.
    Wells, A.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    CASCAT: Redesign of omega-Transaminases for Synthesis of Chiral Amines2010In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 150, p. S123-S124Article in journal (Other academic)
    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.

  • 25.
    Svedendahl, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Sjöstrand, Ulf
    Cambrex Karlskoga AB.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Rational Redesign of ω-Transaminases2010Conference paper (Refereed)
1 - 25 of 25
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