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  • 1.
    Hamberg, Anders
    KTH, School of Biotechnology (BIO).
    Enzyme selectivity as a tool in analytical chemistry2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Enzymes are useful tools as specific analytical reagents. Two different analysis methods were developed for use in the separate fields of protein science and organic synthesis. Both methods rely on the substrate specificity of enzymes. Enzyme catalysis and substrate specificity is described and put in context with each of the two developed methods.

    In paper I a method for C-terminal peptide sequencing was developed based on conventional Carboxypeptidase Y digestion combined with matrix assisted laser desorption/ionization mass spectrometry. An alternative nucleophile was used to obtain a stable peptide ladder and improve sequence coverage.

    In paper II and III, three different enzymes were used for rapid analysis of enantiomeric excess and conversion of O-acylated cyanohydrins synthesized by a defined protocol. Horse liver alcohol dehydrogenase, Candida antarctica lipase B and pig liver esterase were sequentially added to a solution containing the O-acylated cyanohydrin. Each enzyme caused a drop in absorbance from oxidation of NADH to NAD+. The conversion and enantiomeric excess of the sample could be calculated from the relative differences in absorbance.

  • 2.
    Hamberg, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Serine Hydrolase Selectivity: Kinetics and applications in organic and analytical chemistry2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The substrate selectivities for different serine hydrolases were utilized in various applications, presented in papers I-VI. The articles are discussed in the thesis in view of the kinetics of the enzyme catalysis involved.

    In paper I the enantioselectivities towards a range of secondary alcohols were reversed for Candida antarctica lipase B by site directed mutagenesis. The thermodynamic components of the enantioselectivity were determined for the mutated variant of the lipase.

    In papers II-III Candida antarctica lipase B was engineered for selective monoacylation using two different approaches. A variant of the lipase created for substrate assisted catalysis (paper II) and three different variants with mutations which decreased the volume of the active site (paper III) were evaluated. Enzyme kinetics for the different variants were measured and translated into activation energies for comparison of the approaches.

    In papers IV and V three different enzymes were used for rapid analysis of enantiomeric excess and conversion of O-acylated cyanohydrins synthesized by a defined protocol. Horse liver alcohol dehydrogenase, Candida antarctica lipase B and pig liver esterase were sequentially added to a solution containing the O-acylated cyanohydrin. Each enzyme caused a drop in absorbance from oxidation of NADH to NAD+. The product yield and enantiomeric excess was calculated from the relative differences in absorbance.

    In paper VI a method for C-terminal peptide sequencing was developed based on conventional Carboxypeptidase Y digestion combined with matrix assisted laser desorption/ionization mass spectrometry. An alternative nucleophile was used to obtain a stable peptide ladder and improve sequence coverage.

  • 3.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Kempka, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Sjödahl, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Roeraade, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    C-terminal ladder sequencing of peptides using an alternative nucleophile in carboxypeptidase Y digests2006In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 357, no 2, p. 167-172Article in journal (Refereed)
    Abstract [en]

     A method for improved sequence coverage in C-terminal sequencing of peptides, based on carboxypeptidase digestion, is described. In conventional carboxypeptidase digestions, the peptide substrate is usually extensively degraded and a full amino acid sequence cannot be obtained due to the lack of a complete peptide ladder. In the presented method, a protecting group is introduced at the C terminus of a fraction of the peptide fragments formed in the digest, and thereby further degradation of the C-terminally modified peptides are slowed down. The protecting group was attached to the C-terminal amino acid through a carboxypeptidase-catalyzed reaction with an alternative nucleophile, 2-pyridylmethylamine, added to the aqueous digestion buffer. Six peptides were digested by carboxypeptidase Y with and without 2-pyridylmethylamine present in the digest buffer, and the resulting fragments subsequently were analyzed with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Comparison of the two digestion methods showed that the probability of successful ladder sequencing increased, by more than 50% using 2-pyridylmethylamine as a competing nucleophile in carboxypeptidase Y digests.

  • 4.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Penhoat, Maël
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    High-Throughput Enzymatic Method for Enantiomeric Excess Determination of O-Acetylated Cyanohydrins2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 7, p. 2234-2235Article in journal (Refereed)
  • 5.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wingstrand, Erica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    High Throughput Synthesis and Analysis of Acylated Cyanohydrins2007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 15, p. 4334-4341Article in journal (Refereed)
    Abstract [en]

    The yields and optical purities of products obtained from chiral Lewis acid/Lewis base-catalysed additions of alpha-ketonitriles to prochiral aldehydes could be accurately determined by an enzymatic method. The amount of remaining aldehyde was determined after its reduction to an alcohol, whilst the two product enantiomers were analysed after subsequent hydrolysis first by the (S)-selective Candida antarctica lipase B and then by the unselective pig liver esterase. The method could be used for analysis of products obtained from a number of aromatic aldehydes and aliphatic ketonitriles. Microreactor technology was successfully combined with high-throughput analysis for efficient catalyst optimization.

  • 6.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Magnusson, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hu, Francis J.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    Selective monoacylation of diols by substrate assisted catalysis in T40A CALBManuscript (preprint) (Other academic)
  • 7.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Magnusson, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hu, Francis J.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Selective Monoacylation of Diols by Substrate Assisted Catalysis in T40A Candida antarctica Lipase B2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 3, p. 743-747Article in journal (Refereed)
    Abstract [en]

    The selectivity towards diols over monoesters in the esterification of diols catalysed by lipase B from Candida antarctica (CALB) was improved by the single point mutation T40A in the enzyme's oxyanion hole. Substrate-assisted catalysis was suggested from molecular modelling of the tetrahedral intermediate in esterification of 1,2-ethanediol catalysed by T40A CALB. The non-reacting hydroxyl group of the diol forms a hydrogen bond to the oxyanion in the transition state, replacing that deleted in mutation. Monoester yields in transacylation reactions were monitored over time to compare the selectivities for wild-type and T40A CALB. The results showed increased selectivities towards the diols tested over their corresponding monoesters as a result of the T40A mutation with substrate-assisted catalysis as a plausible explanation.

  • 8.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Maurer, S.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Rational engineering of Candida antarctica lipase B for selective monoacylation of diols2012In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 48, no 80, p. 10013-10015Article in journal (Refereed)
    Abstract [en]

    The enzyme Candida antarctica lipase B was subjected to site directed mutagenesis suggested by molecular modelling. The selectivity for the enzyme increased towards a range of diols over their corresponding monoesters as an effect of the mutations.

  • 9.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Maurer, Steffen
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Rational engineering of CALB for selective monoacylation of diolsManuscript (preprint) (Other academic)
  • 10.
    Lundgren, Stina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wingstrand, Erica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hamberg, Anders
    KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Hult, Karl
    KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    ORGN 402-Dual activation in enantioselective synthesis of cyanohydrins2006In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 232Article in journal (Other academic)
  • 11.
    Magnusson, Anders O.
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Takwa, Mohamad
    KTH, School of Biotechnology (BIO), Biochemistry.
    Harnberg, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    An S-selective lipase was created by rational redesign and the enantioselectivity increased with temperature2005In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 44, no 29, p. 4582-4585Article in journal (Refereed)
    Abstract [en]

    Higher activity with larger pockets: The figure shows a superposition of intermediates that occur in acyl transfer to (S)-1-phenylethanol catalyzed by Candida antarctica lipase B (CALB). Wild-type CALB cannot accomodate the phenyl group (gray) in the stereospecificity pocket and form all of the catalytically essential H bonds. The Trp 104 Ala mutation liberates the volume in yellow, the S enantiomer is easily fitted, and the specificity constant increases by a factor of 130 000.

  • 12.
    Wingstrand, Erica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hamberg, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    655-ORGN - Synthesis of highly enantioenriched cyanohydrins by dual Lewis acid - Lewis base activation2007In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234, p. 655-ORGN-Article in journal (Other academic)
    Abstract [en]

    Enantioenriched acylated cyanohydrins serve as versatile synthons and are themselves important synthetic targets.  By using our efficient catalytic dual Lewis acid - Lewis base activation system, a range of α-ketonitriles were added to both arom. and aliph. aldehydes affording highly enantioenriched O-acylated cyanohydrins in excellent yields.  The reactions proceeded smoothly in only one step with perfect atom economy.  Our recent results as well as the scope and limitations of the system will be presented together with mechanistic aspects.

1 - 12 of 12
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