Sulfated phenolic acids in plants.

Sulfated phenolic acids are widely occurring metabolites in plants, including fruits, vegetables and crops. The untargeted UHPLC-QTOF-MS metabolomics of more than 50 samples from plant, fungi and algae lead to the discovery of a small group of sulfated metabolites derived from phenolic acids. These compounds were detected in land plants for the first time.

Chemoenzymatic Hunsdiecker-Type Decarboxylative Bromination of Cinnamic Acids.

In this contribution, we report chemoenzymatic bromodecarboxylation (Hunsdiecker-type) of α,ß-unsaturated carboxylic acids. The extraordinarily robust chloroperoxidase from (VCPO) generated hypobromite from HO and bromide, which then spontaneously reacted with a broad range of unsaturated carboxylic acids and yielded the corresponding vinyl bromide products. Selectivity issues arising from the (here undesired) addition of water to the intermediate bromonium ion could be solved by reaction medium engineering.

Water-Soluble Anthraquinone Photocatalysts Enable Methanol-Driven Enzymatic Halogenation and Hydroxylation Reactions.

Peroxyzymes simply use HO as a cosubstrate to oxidize a broad range of inert C-H bonds. The lability of many peroxyzymes against HO can be addressed by a controlled supply of HO, ideally in situ. Here, we report a simple, robust, and water-soluble anthraquinone sulfonate (SAS) as a promising organophotocatalyst to drive both haloperoxidase-catalyzed halogenation and peroxygenase-catalyzed oxyfunctionalization reactions.

Chemoenzymatic Halocyclization of 4-Pentenoic Acid at Preparative Scale.

The scale-up of chemoenzymatic bromolactonization to 100 g scale is presented, together with an identification of current limitations. The preparative-scale reaction also allowed for meaningful mass balances identifying current bottlenecks of the chemoenzymatic reaction.

Chemoenzymatic Halocyclization of γ,δ-Unsaturated Carboxylic Acids and Alcohols.

Invited for this month's cover is the group of Prof. Dr. Frank Hollmann at Delft University of Technology in the Netherlands.

Chemoenzymatic Halocyclization of γ,δ-Unsaturated Carboxylic Acids and Alcohols.

A chemoenzymatic method for the halocyclization of unsaturated alcohols and acids by using the robust V-dependent chloroperoxidase from Curvularia inaequalis (CiVCPO) as catalyst has been developed for the in situ generation of hypohalites. A broad range of halolactones and cyclic haloethers are formed with excellent performance of the biocatalyst.

Marine Vanadium-Dependent Haloperoxidases, Their Isolation, Characterization, and Application.

Vanadium-dependent haloperoxidases in seaweeds, cyanobacteria, fungi, and possibly phytoplankton play an important role in the release of halogenated volatile compounds in the environment. These halocarbons have effects on atmospheric chemistry since they cause ozone depletion. In this chapter, a survey is given of the different sources of these enzymes, some of their properties, the various methods to isolate them, and the bottlenecks in purification.

Selective aerobic oxidation reactions using a combination of photocatalytic water oxidation and enzymatic oxyfunctionalisations.

Peroxygenases offer attractive means to address challenges in selective oxyfunctionalisation chemistry. Despite their attractiveness, the application of peroxygenases in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant (HO). Often atom inefficient peroxide generation systems are required, which show little potential for large scale implementation.

Vanadium Chloroperoxidases: The Missing Link in the Formation of Chlorinated Compounds and Chloroform in the Terrestrial Environment?

It is well established that the majority of chlorinated organic substances found in the terrestrial environment are produced naturally. The presence of these compounds in soils is not limited to a single ecosystem. Natural chlorination is also a widespread phenomenon in grasslands and agricultural soils typical for unforested areas.

Halofunctionalization of alkenes by vanadium chloroperoxidase from Curvularia inaequalis.

The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as reaction products is presented.

Dissolving Lignin in Water through Enzymatic Sulfation with Aryl Sulfotransferase.

We introduce the concept of using site-specific sulfation of various lignins for increasing their aqueous solubility and thereby their processability. Using p-nitrophenylsulfate as a sulfate source and an aryl sulfotransferase enzyme as catalyst, lignins are easily sulfated at ambient conditions. We demonstrate the specific sulfation of phenolic hydroxyl groups on five different lignins: Indulin AT (Kraft softwood), Protobind 1000 (mixed wheat straw/Sarkanda grass soda) and three organosolv lignins.

⁵¹V NMR Crystallography of Vanadium Chloroperoxidase and Its Directed Evolution P395D/L241V/T343A Mutant: Protonation Environments of the Active Site.

Vanadium-dependent haloperoxidases (VHPOs) perform two-electron oxidation of halides using hydrogen peroxide. Their mechanism, including the factors determining the substrate specificity and the pH-dependence of the catalytic rates, is poorly understood. The vanadate cofactor in the active site of VHPOs contains "spectroscopically silent" V(V), which does not change oxidation state during the reaction.

The role of vanadium haloperoxidases in the formation of volatile brominated compounds and their impact on the environment.

Vanadium haloperoxidases differ strongly from heme peroxidases in substrate specificity and stability and in contrast to a heme group they contain the bare metal oxide vanadate as a prosthetic group. These enzymes specifically oxidize halides in the presence of hydrogen peroxide into hypohalous acids. These reactive halogen intermediates will react rapidly and aspecifically with many organic molecules.

Synthesis of carbohydrates in a continuous flow reactor by immobilized phosphatase and aldolase.

Herein, we report a new flow process with immobilized enzymes to synthesize complex chiral carbohydrate analogues from achiral inexpensive building blocks in a three-step cascade reaction. The first reactor contained immobilized acid phosphatase, which phosphorylated dihydroxyacetone to dihydroxyacetone phosphate using pyrophosphate as the phosphate donor. The second flow reactor contained fructose-1,6-diphosphate aldolase (RAMA, rabbit muscle aldolase) or rhamnulose-1-phosphate aldolase (RhuA from Thermotoga maritima) and acid phosphatase.

Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation.

Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling.

Selective oxidative decarboxylation of amino acids to produce industrially relevant nitriles by vanadium chloroperoxidase.

Industrial nitriles from biomass: Vanadium-chloroperoxidase is successfully used to transform selectively glutamic acid into 3-cyanopropanoic acid, a key intermediate for the synthesis of bio-succinonitrile and bio-acrylonitrile, by using a catalytic amount of a halide salt. This clean oxidative decarboxylation can be applied to mixtures of amino acids obtained from plant waste streams, leading to easily separable nitriles.

Continuous-flow reactor-based enzymatic synthesis of phosphorylated compounds on a large scale.

Acid phosphatase, an enzyme that is able to catalyze the transfer of a phosphate group from cheap pyrophosphate to alcoholic substrates, was covalently immobilized on polymethacrylate beads with an epoxy linker (Immobeads-150 or Sepabeads EC-EP). After immobilization 70% of the activity was retained and the immobilized enzyme was stable for many months. With the immobilized enzyme we were able to produce and prepare D-glucose-6-phosphate, N-acetyl-D-glucosamine-6-phosphate, allyl phosphate, dihydroxyacetone phosphate, glycerol-1-phosphate, and inosine-5'-monophosphate from the corresponding primary alcohol on gram scale using either a fed-batch reactor or a continuous-flow packed-bed reactor.

Vanadium K-edge XAS studies on the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis.

Vanadium K-edge X-ray Absorption Spectra have been recorded for the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis at pH 6.0. The Extended X-ray Absorption Fine Structure (EXAFS) regions provide a refinement of previously reported crystallographic data; one short V=O bond (1.

Improvement of an acid phosphatase/DHAP-dependent aldolase cascade reaction by using directed evolution.

To enhance the phosphorylating activity of the bacterial nonspecific acid phosphatase from Salmonella enterica ser. typhimurium LT2 towards dihydroxyacetone (DHA), a mutant library was generated from the native enzyme. Three different variants that showed enhanced activity were identified after one round of epPCR.

Synergy between chemo- and bio-catalysts in multi-step transformations.

Cascade synthetic pathways, which allow multi-step conversions to take place in one reaction vessel, are crucial for the development of biomimetic, highly efficient new methods of chemical synthesis. Theoretically, the complexity introduced by combining processes could lead to an improvement of the overall process; however, it is the current general belief that it is more efficient to run processes separately. Inspired by natural cascade procedures we successfully combined a lipase catalyzed amidation with palladium catalyzed coupling reactions, simultaneously carried out on the same molecule.

Crystal structure of a trapped phosphate intermediate in vanadium apochloroperoxidase catalyzing a dephosphorylation reaction.

The crystal structure of the apo form of vanadium chloroperoxidase from Curvularia inaequalis reacted with para-nitrophenylphosphate was determined at a resolution of 1.5 A. The aim of this study was to solve structural details of the dephosphorylation reaction catalyzed by this enzyme.

Simple enzymatic in situ generation of dihydroxyacetone phosphate and its use in a cascade reaction for the production of carbohydrates: increased efficiency by phosphate cycling.

A new enzymatic method for the generation of dihydroxyacetone phosphate (DHAP) using the acid phosphatase from Shigella flexneri (PhoN-Sf) and the cheap phosphate donor pyrophosphate (PPi) is described. The utility of this method was demonstrated in an aldolase-catalyzed condensation carried out in one pot in which DHAP was generated and coupled to propionaldehyde to give a yield of 53% of the isolated dephosphorylated end product.

51V solid-state magic angle spinning NMR spectroscopy of vanadium chloroperoxidase.

We report 51V solid-state NMR spectroscopy of the 67.5-kDa vanadium chloroperoxidase, at 14.1 T.

Laboratory-evolved vanadium chloroperoxidase exhibits 100-fold higher halogenating activity at alkaline pH: catalytic effects from first and second coordination sphere mutations.

Directed evolution was performed on vanadium chloroperoxidase from the fungus Curvularia inaequalis to increase its brominating activity at a mildly alkaline pH for industrial and synthetic applications and to further understand its mechanism. After successful expression of the enzyme in Escherichia coli, two rounds of screening and selection, saturation mutagenesis of a "hot spot," and rational recombination, a triple mutant (P395D/L241V/T343A) was obtained that showed a 100-fold increase in activity at pH 8 (k(cat) = 100 s(-1)). The increased K(m) values for Br(-) (3.

The enzymatic component of Drosophila melanogaster chorion is the Pxd peroxidase.

In the present study, we demonstrate the isolation and characterization of the Pxd cDNA clone, which codes for the Drosophila melanogaster chorion peroxidase. This specific peroxidase is involved in the chorion hardening process, through protein crosslinking mediated by the formation of di- and tri-tyrosine bonds. The Pxd gene product has been identified in crude protein extracts from adult flies as three immunoreacting, with the anti-rAePO polyclonal antibody, bands of 77, 67 and 55 kDa, while in larvae and purified chorions as a unique 55 kDa band.