Asymmetric whole-cell bioreduction of an α,β-unsaturated aldehyde (citral): competing prim-alcohol dehydrogenase and C–C lyase activities

Hall, Mélanie; Hauer, Bernhard; Stuermer, Rainer; Kroutil, Wolfgang; Faber, Kurt

doi:10.1016/j.tetasy.2006.11.018

Cited by 81 publications

(50 citation statements)

References 24 publications

(18 reference statements)

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“…Both the non-activated C=C bond and the aldehyde moiety remained untouched, which is in contrast to whole-cell bioreduction. [10,18] However, when NADH was recycled using the FDH/formate system, the aldehyde moiety was rapidly reduced to furnish (S)-citronellol (3,7-dimethyloct-6-ene-1-ol, ee > 95%) and nerol (3,7-dimethylocta-2,6-dien-1-ol) as the major products (entry 2). This drawback -presumably caused by prim-ADH activities present in commercial FDH preparations [crude NAD + -specific FDH preparations from Jülich Fine Chemicals (No.…”

Section: Resultsmentioning

confidence: 99%

“…[8] Overall, the reaction resembles an asymmetric conjugate (Michael-type) addition of a chiral hydride onto an enone and thus, non-activated C=C bonds are completely unreactive. [9,10,18] In order to avoid the requirement for external NAD(P)H recycling, the vast majority of asymmetric C=C-bioreductions were performed using whole fermenting cells, usually bakers yeast. [11] Although the stereoselectivities thus obtained were often excellent, the chemoselectivities with respect to C=C versus C=O reduction were severely impeded by the action of competing carbonyl reductases, which not only depleted the substrate (by forming allylic alcohols as dead-end products) but also the product (furnishing saturated alcohols due to "over-reduction").…”

Section: Introductionmentioning

confidence: 99%

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Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Hall¹,

Stueckler²,

Ehammer³

et al. 2008

Adv Synth Catal

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183

186

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Three cloned enoate reductases from the "old yellow enzyme" family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing a,b-unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity -only the conjugated C=C bond was reduced, while isolated olefins and carbonyl groups remained intact -with excellent stereoselectivities (ees up to > 99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this "enzymebased stereocontrol" is caused by subtle differences within the active site geometries.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Hall¹,

Stueckler²,

Ehammer³

et al. 2008

Adv Synth Catal

Self Cite

183

186

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“…Even so, the whole-cell catalyzed reduction of ␣,␤-unsaturated carbonyl compounds can be complex and hampered by competing enzymatic reactions (8). Thus, in the asymmetric bioreduction of citral to the ␣,␤-saturated aldehyde citronellal, the undesirable by-products nerol, geraniol, and citronellol were formed due to the action of competing alcohol dehydrogenases and citral lyase activity (9); in stereoselective biocatalytic reduction of ␣-ionone by Glomerella cingulata, (6S,9R)-␣-ionol was produced, some of which was subsequently hydrogenated by enoate reductase to form (6S,9R)-7,8-dyhidro-␣-ionol (10); and with use of ␣,␤-unsaturated aldehydes as the substrate, the aldehyde oxidation catalyzed by aldehyde dehydrogenase usually led to the formation of undesirable ␣,␤-unsaturated carboxylic acids (11,12). Therefore, novel biocatalysts with high chemoselectivity are needed for synthesis of ␣,␤-unsaturated alcohols.…”

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confidence: 99%

Characterization of an Allylic/Benzyl Alcohol Dehydrogenase from Yokenella sp. Strain WZY002, an Organism Potentially Useful for the Synthesis of α,β-Unsaturated Alcohols from Allylic Aldehydes and Ketones

Ying

Wang

Xiong

et al. 2014

Appl Environ Microbiol

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A novel whole-cell biocatalyst with high allylic alcohol-oxidizing activities was screened and identified as Yokenella sp. WZY002, which chemoselectively reduced the CAO bond of allylic aldehydes/ketones to the corresponding ␣,␤-unsaturated alcohols at 30°C and pH 8.0. The strain also had the capacity of stereoselectively reducing aromatic ketones to (S)-enantioselective alcohols. The enzyme responsible for the predominant allylic/benzyl alcohol dehydrogenase activity was purified to homogeneity and designated YsADH (alcohol dehydrogenase from Yokenella sp.), which had a calculated subunit molecular mass of 36,411 Da. The gene encoding YsADH was subsequently expressed in Escherichia coli, and the purified recombinant YsADH protein was characterized. The enzyme strictly required NADP(H) as a coenzyme and was putatively zinc dependent. The optimal pH and temperature for crotonaldehyde reduction were pH 6.5 and 65°C, whereas those for crotyl alcohol oxidation were pH 8.0 and 55°C. The enzyme showed moderate thermostability, with a half-life of 6.2 h at 55°C. It was robust in the presence of organic solvents and retained 87.5% of the initial activity after 24 h of incubation with 20% (vol/vol) dimethyl sulfoxide. The enzyme preferentially catalyzed allylic/benzyl aldehydes as the substrate in the reduction of aldehydes/ketones and yielded the highest activity of 427 U mg ؊1 for benzaldehyde reduction, while the alcohol oxidation reaction demonstrated the maximum activity of 79.9 U mg ؊1 using crotyl alcohol as the substrate. Moreover, kinetic parameters of the enzyme showed lower K m values and higher catalytic efficiency for crotonaldehyde/benzaldehyde and NADPH than for crotyl alcohol/benzyl alcohol and NADP ؉ , suggesting the nature of being an aldehyde reductase.

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“…Key steps of this route are the enantioselective reduction of citral to (R)-citronellal (3,7-dimethyl-oct-6-enal) and the subsequent cyclization to isopulegol. With enzymes like the socalled old yellow enzymes (e.g., OYE 2 [16]), the conversion of citral to citronellal has already been achieved, and ee values of Ͼ99% and product concentrations of 50 g/liter have been demonstrated (9,15). Unfortunately, the strict dependence of class I terpene synthases on phosphorylated precursors for the subsequent cyclization reaction limits the technical applicability of this group of enzymes.…”

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confidence: 99%

Activation-Independent Cyclization of Monoterpenoids

Siedenburg

Jendrossek

Breuer

et al. 2012

Appl Environ Microbiol

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The biosynthesis of cyclic monoterpenes (C 10 ) generally requires the cyclization of an activated linear precursor (geranyldiphosphate) by specific terpene cyclases. Cyclic triterpenes (C 30 ), on the other hand, originate from the linear precursor squalene by the action of squalene-hopene cyclases (SHCs) or oxidosqualene cyclases (OSCs). Here, we report a novel terpene cyclase from Zymomonas mobilis (ZMO1548-Shc) with the unique capability to cyclize citronellal to isopulegol. To our knowledge, ZMO1548-Shc is the first biocatalyst with diphosphate-independent monoterpenoid cyclase activity. A combinatorial approach using site-directed mutagenesis and modeling of the active site with a bound substrate revealed that the cyclization of citronellal proceeds via a different mechanism than that of the cyclization of squalene.T erpenoids are widespread secondary metabolites present in nearly all organisms. They have important or even essential functions in metabolism and act, for example, as membrane stabilizers, hormones, vitamins, or photoactive compounds. Terpenes are composed of isoprene units that are synthesized either via the mevalonate pathway (13) or via the 1-deoxy-D-xylulose-5-phosphate (DXP) route (12). The common linear precursor of all monoterpenes and higher terpenoids is geranyldiphosphate (30), independent from the pathway used for the synthesis of the isoprene backbone (isopentenyldiphosphate). Terpenoids are present in nature in a large variety of both linear and cyclic forms. The formation of the ring structure of cyclic terpenoids from diphosphate-activated linear precursors is catalyzed by terpene cyclases (terpene synthases) that are specific for either geranyldiphosphate (C 10 ) (monoterpene cyclases), farnesyldiphosphate (C 15 ) (sesquiterpene cyclases), or geranyl-geranyldiphosphate (C 20 ) (diterpene cyclases). Activation by diphosphate is essential for all cyclization reactions catalyzed by class I terpene cyclases. For all currently known diphosphate-dependent cyclizations, the reaction requires the Lewis acid (Mg 2ϩ )-catalyzed ionization of the diphosphate ester of the respective precursor. After isomerization and the subsequent elimination of the diphosphate group, a primary carbocation is generated, which subsequently attacks a nearby double bond, leading to the formation of the more stable carbenium ion (R 3 C ϩ -). Finally, the reaction is terminated by deprotonation, leading to a vast variety of cyclic terpenoids (1, 5, 6).Cyclic triterpenes, such as hopanoids in bacteria or sterols in eukaryotes, arise either from the nonactivated linear precursor squalene (C 30 ) or from 2,3-oxidosqualene. The polycyclization reaction is catalyzed by squalene-hopene cyclases (SHCs), lanosterol synthases, or oxidosqualene cyclases, respectively (21, 25). The cyclization reaction of squalene involves the concerted formation of (i) five ring structures, (ii) 13 carbon-carbon bonds, and (iii) nine stereocenters, rendering it one of the most complex single-step reactions known in biochemistry. Remarka...

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Asymmetric whole-cell bioreduction of an α,β-unsaturated aldehyde (citral): competing prim-alcohol dehydrogenase and C–C lyase activities

Cited by 81 publications

References 24 publications

Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Characterization of an Allylic/Benzyl Alcohol Dehydrogenase from Yokenella sp. Strain WZY002, an Organism Potentially Useful for the Synthesis of α,β-Unsaturated Alcohols from Allylic Aldehydes and Ketones

Activation-Independent Cyclization of Monoterpenoids

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