- Artificial Light-Harvesting Complexes Enable Rieske Oxygenase Catalyzed Hydroxylations in Non-Photosynthetic cells
-
In this study, we coupled a well-established whole-cell system based on E. coli via light-harvesting complexes to Rieske oxygenase (RO)-catalyzed hydroxylations in vivo. Although these enzymes represent very promising biocatalysts, their practical applicability is hampered by their dependency on NAD(P)H as well as their multicomponent nature and intrinsic instability in cell-free systems. In order to explore the boundaries of E. coli as chassis for artificial photosynthesis, and due to the reported instability of ROs, we used these challenging enzymes as a model system. The light-driven approach relies on light-harvesting complexes such as eosin Y, 5(6)-carboxyeosin, and rose bengal and sacrificial electron donors (EDTA, MOPS, and MES) that were easily taken up by the cells. The obtained product formations of up to 1.3 g L?1 and rates of up to 1.6 mm h?1 demonstrate that this is a comparable approach to typical whole-cell transformations in E. coli. The applicability of this photocatalytic synthesis has been demonstrated and represents the first example of a photoinduced RO system.
- Bloh, Jonathan Z.,Burek, Bastien O.,Feyza ?zgen, F.,Kourist, Robert,Runda, Michael E.,Schmidt, Sandy,Wied, Peter
-
p. 3982 - 3987
(2020/02/04)
-
- Engineering Rieske Non-Heme Iron Oxygenases for the Asymmetric Dihydroxylation of Alkenes
-
The asymmetric dihydroxylation of olefins is of special interest due to the facile transformation of the chiral diol products into valuable derivatives. Rieske non-heme iron oxygenases (ROs) represent promising biocatalysts for this reaction as they can be engineered to efficiently catalyze the selective mono- and dihydroxylation of various olefins. The introduction of a single point mutation improved selectivities (≥95 %) and conversions (>99 %) towards selected alkenes. By modifying the size of one active site amino acid side chain, we were able to modulate the regio- and stereoselectivity of these enzymes. For distinct substrates, mutants displayed altered regioselectivities or even favored opposite enantiomers compared to the wild-type ROs, offering a sustainable approach for the oxyfunctionalization of a wide variety of structurally different olefins. Modulation by mutation: Rieske non-heme iron oxygenases can be used as efficient biocatalysts for the selective oxyfunctionalization of various olefins yielding vicinal cis-diols and allylic alcohols. Introduction of a single amino acid substitution in the active sites of two selected oxygenases resulted in variants with improved stereoselectivities and product formations.
- Gally, Christine,Nestl, Bettina M.,Hauer, Bernhard
-
supporting information
p. 12952 - 12956
(2015/11/02)
-
- New synthesis of A-ring aromatic strigolactone analogues and their evaluation as plant hormones in pea (pisum sativum)
-
A new general access to A-ring aromatic strigolactones, a new class of plant hormones, has been developed. The key transformations include in sequence ring-closing metathesis, enzymatic kinetic resolution and a radical cyclization with atom transfer to install the tricyclic ABC-ring system. The activity as plant hormones for the inhibition of shoot branching in pea of various analogues synthesized by this strategy is reported. Inhibiting shoot branching: A new general access to A-ring aromatic strigolactones (see scheme), a new class of plant hormones, has been developed. The biological activity of various analogues synthesized by this strategy for inhibiting bud outgrowth in pea was evaluated. Copyright
- Chen, Victor X.,Boyer, Fran?ois-Didier,Rameau, Catherine,Pillot, Jean-Paul,Vors, Jean-Pierre,Beau, Jean-Marie
-
p. 4849 - 4857
(2013/05/22)
-
- The effect of encapsulated Zn-POM on the catalytic activity of MIL-101 in the oxidation of alkenes with hydrogen peroxide
-
Zinc monosubstituted Keggin heteropolyanion [PZnMo2W 9O39]5- was electrostatically bound to nanocages of MIL-101 polymer matrix. The Zn-POM@MIL-101 catalyst was characterized by XRD, N2 adsorption, atomic absorption (AAS), and FT-IR spectroscopic methods. The catalytic activity of the new composite material, Zn-POM@MIL-101, was assessed in the oxidation of alkenes using aqueous hydrogen peroxide as oxidant. Zn-POM@MIL-101/H2O2 catalytic system demonstrated good catalytic activity in the oxidation reactions. Zn-POM@MIL-101 was reusable for three catalytic cycles. While the MIL-101 matrix is an active catalyst in these oxidation reactions, the presence of Zn-POM significantly changed the selectivity and reaction times. Copyright
- Saedi, Zahra,Tangestaninejad, Shaharm,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
experimental part
p. 463 - 473
(2012/05/20)
-
- Enantioselective Bacterial Biotransformation Routes to cis-Diol Metabolites of Monosubstituted Benzenes, Naphthalene and Benzocycloalkenes of Either Absolute Configuration
-
Enzyme-catalysed kinetic resolution and asymmetric dihydroxylation routes to enantiopure cis-diol metabolites of arenes and benzocycloalkenes of either absolute configuration have been developed using appropriate strains of the bacterium Pseudomonas putida.
- Allen, Christopher C. R.,Boyd, Derek R.,Dalton, Howard,Sharma, Narain D.,Brannigan, Ian,et al.
-
p. 117 - 118
(2007/10/02)
-
- Novel (α,β-Epoxyalkyl)lithium Reagents via the Lithiation of Organyl-Substituted Epoxides
-
A series of epoxides bearing unsaturated organyl groups attached directly to the epoxy group was found to have sufficient kinetic acidity to undergo clean lithiation at low temperatures.Epoxides of the type is aryl, vinylic, acetylenic, alkoxycarbonyl, or cyano, were smoothly converted into by either t-BuLi or LDA in the temperature range of -80 to -115 deg C.The resulting (α,β-epoxyalkyl)lithium reagents could be transformed into a variety of substituted epoxides, such as R2C-CE(Un)-O, where E = D, R3Si, R3Sn, R, RCO, CO2H, or COH(R)2.In cases where Un is acyl, addition to the carbonyl, rather than lithiation, occurred preferentially.Attempted lithiations of aziridines and thiiranes led to extrusion of nitrogen and sulfur, respectively.Even the relatively stable intermediates generated at -90 deg C underwent carbenoid-like decomposition at higher temperatures to yield isomerization and intermolecular-insertion products.Observation of these processes gives direct corroboration of reaction mechanisms proposed for the base-promoted isomerizations of epoxides.
- Eisch, John J.,Galle, James E.
-
p. 4835 - 4840
(2007/10/02)
-
- Tautomerism of the Monohydroxy Derivatives of Five-Membered O, N, and S Heterocycles
-
The O-deuterated enolic tautomers 3-deuteroxybenzofuran, 3-deuteroxybenzothiophene, 3-deuteroxyindole, 3-deuteroxy-1-methylindole, 3-deuteroxyfuran, 3-deuteroxythiophene, 2-deuteroxybenzothiophene, and 2-deuteroxythiophene have been generated in solution in mixtures of CD3COCD3, CD3CN, or CD3SOCD3 with D2O by hydrolysis of their trimethylsilyl derivatives in the presence of DCl (1E-3 - 1E-4 M) and characterized by 1H NMR spectroscopy.Solutions of 3-hydroxypyrrole and of 3-hydroxy-1-methylpyrrole were obtained by methanolysis of their trimethylsilyl derivatives,evaporation of the methanol, and immediate dissolution in DMSO-d6.The carbocyclic analogues of the bicyclic heterocyclic enols 3-deuteroxyindene and 2-deuteroxyindene were also generated in solution.Attempts to prepare solutions of 2-deuteroxyfuran, 2-deuteroxypyrrole, and 2-deuteroxy-1-methylpyrrole were unsuccessful.The kinetics of ketonization of the OH forms of these enols have been investigated in water or aqueous acetonitrile solution.The equilibrium constants for the keto-enol tautomerism were also determined either by direct measurement when sufficient enol was present at equilibrium or as the ratio of the rate constant for enolization of the keto form to that for ketonization of the enol form, the former being determined by the iodine-trapping technique.The effect of solvent on the equilibrium constants was also studied.Sufficient data were available for the equilibrium between 3-hydroxyindole and 3-ketoindole for them to be analyzed by the four-parameter equation of Mills and Beak to yield an a value of 2.4 and a b value of -3.0.The pKas of the bicyclic enols were measured. 3-Hydroxybenzofuran and3-hydroxybenzothiophene are stronger acids than 3-hydroxyindole and 3-hydroxy-1-methylindole.The ketonization reactions are general acid and general base catalyzed and their mechanisms are discussed.
- Capon, Brian,Kwok, Fu-Chiu
-
p. 5346 - 5356
(2007/10/02)
-
- Oxidation of Styrene Derivatives by S2O82--CuII in Acetic Acid and Acetonitrile. Reaction Paths in Oxidations via Radical Cations
-
β-Aryl carbonyl compounds are major products in the oxidation of a variety of styrene derivatives by S2O82--CuII.Evidence is presented that they arise via oxidation to a radical cation, nucleophilic addition of water to give a β-hydroxyalkyl radical, CuII oxidation to epoxide, and finally acid-catalyzed rearrangement.Data on oxidation of alkyl aromatics with additional functional groups are presented.With ether and amino groups, oxidation occurs at the functional group even when it is remote from the aryl nucleus.These and previous data are summarized to give a coherent picture of the various paths by which aryl side chains may be degraded via initial radical cation intermediates.
- Walling, Cheves,El-Taliawi, Gamil M.,Amarnath, Kalyani
-
p. 7573 - 7578
(2007/10/02)
-