Stereoselective synthesis of γ-hydroxynorvaline through combination of organo- and biocatalysis

An efficient route for the synthesis of all four diastereomers of PMP-protected α-amino-γ-butyrolacton to access γ-hydroxynorvaline was established. The asymmetric key steps comprise an organocatalytic Mannich reaction and an enzymatic ketone reduction. Three reaction steps could be integrated in a one-pot process, using 2-PrOH both as solvent and as reducing agent. The sequential construction of stereogenic centres gave access to each of the four stereoisomers in high yield and with excellent stereocontrol

Research on industrial biotechnology within the CLIB-Graduate Cluster - Part I

Pietruszka J, Pühler A, Schembecker G. Research on industrial biotechnology within the CLIB-Graduate Cluster - Part I. Journal of Biotechnology. 2012;159(3):121-122

Biochemical parameters of recombinant LipT and LipS determined using 4-nitrophenol-decanoate (C10) for LipT and –octanoate (C8) for LipS.

<p>The measurements were performed at 75 and 70°C, respectively, in 0.1 M PB pH 8.0.</p><p>Data are mean values of three independent measurements.</p

Temperature optimum (A) and thermal stability (B) of LipS and LipT.

<p>Data are mean values of at least three independent measurements and bars indicate the standard deviation. Temperature range and optimum of LipS and LipT were measured with <i>p</i>NP-dodecanoate at temperatures ranging from 20°C to 90°C for 10 min. Assays were performed by incubation of the enzymes at 70°C for up to 72 hours and by measuring residual activities with <i>p</i>NP-dodecanoate at 70°C (LipS) and 75°C (LipT).</p

Esterification reactions between 1-propanol and lauric acid (20 mmol each) as well as 1-tetradecanol and myristic acid (15 mmol each).

<p>Synthesis reactions were catalyzed by LipS and CalB (purchased from Sigma-Aldrich, Buchs, Switzerland) under solvent-free conditions at 70°C. Specific activities of LipS and CalB refer to the dry-weights of the lyophilisates. Data are mean values of at least three independent measurements and bars indicate the standard deviation.</p

Phylogenetic tree illustrating the sorting of 40 metagenome derived lipase/esterase sequences into the eight known lipase/esterase families [<b>61</b>].

<p>The eight families are color coded and labeled with the respective family name (LipS, LipT) or number (I-VIII). The five subfamilies containing the 11 unassignable metagenome lipase/esterase sequences are shown in white and are labeled with the respective family name (UF1-UF5). For the reference sequences, the full organism name as well as the accession number is given at the respective clade. Metagenome sequences are labeled with their protein name and accession number, respectively.</p

HPLC-MS measurement of LipS catalyzing (<i>R</i>)-selectively the hydrolysis of ibuprofen phenyl ester.

<p>The products of the reaction were converted to the corresponding methyl esters for measurement.</p

Substrate spectrum of LipS and LipT shown as relative activity on 4-nitrophenyl (<i>p</i>NP) esters with fatty acid chains of 4 to 18 C-atoms.

<p>Reactions were incubated at 70°C (LipS) or 75°C (LipT) with final substrate concentrations of 1 mM in potassium phosphate buffer (PB, 0.1 M, pH 8.0). Extinction was measured at 405 nm against an enzyme-free blank. Data are mean values of at least three independent measurements and bars indicate the standard deviation.</p

Topology of the inserted domains of α/β-hydrolases.

<p>Superimposition of the inserted domain of LipS (in red) with <b>A)</b> Est1E (2WTM, orange) and LJ0536 (3PF8, turquoise), <b>B)</b> human MGL (3PE6, purple) and <b>C)</b> EstD (3DKR, blue) and Est30 (1TQH, green). The core structure of LipS is indicated in grey and catalytic S126 in yellow. The core structures of LipS homologues are not shown for simplicity.</p