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Analyses of the Cambridge Structural Database and theoretical calculations (PBE0‐D3/def2‐TZVP level, atoms‐in‐molecules, natural bond orbital studies) prove the formation of net attractive noncovalent interactions between group 5 elements and electron‐rich atoms (neutral or anionic). These kinds of bonding are markedly different from coordination bonds formed by the same elements and possess the distinctive features of σ‐hole interactions. The term erythronium bond is proposed to denote these bonds. X‐ray structures of vanadate‐dependent bromoperoxidases show that these interactions are present also in biological systems. [ABSTRACT FROM AUTHOR]

Resumen: Los estudios en el laboratorio han permitido identificar cambios del metabolismo de halógenos en suero y líquido cefalorraquídeo (LCR) de pacientes con enfermedad de Parkinson, que indican la presencia de «autohalogenación acelerada» del LCR de los pacientes o aumento de haloperoxidasas, en concreto, tiroperoxidasa en sangre y lactoperoxidasa en LCR. Además, se ha detectado un exceso en suero y LCR de algunos derivados halogenados, como proteínas con halogenación avanzada tipo advanced oxidation protein products (AOPP). Estos hechos, «autohalogenación acelerada» e incremento de haloperoxidasas y proteínas AOPP, indican la presencia de estrés halogenativo en la enfermedad de Parkinson. Además, un derivado halogenado, la 3-yodo-L-tirosina, muestra toxicidad parkinsoniana en modelos experimentales, pues se ha observado que induce agregados de α-sinucleína y daño de las neuronas de dopamina en cerebro e intestino en ratones. La hipótesis que se maneja es que en la enfermedad de Parkinson existe un exceso halogenativo, relacionado con una alteración haloenzimática de síntesis o degradación de oxiácidos de halógenos y sus derivados halogenados. Este estrés halogenativo se relacionaría con el daño del sistema nervioso. Abstract: Laboratory studies identified changes in the metabolism of halogens in the serum and cerebrospinal fluid (CSF) of patients with Parkinson's disease, which indicates the presence of «accelerated self-halogenation» of CSF and/or an increase in haloperoxidases, specifically serum thyroperoxidase and CSF lactoperoxidase. Furthermore, an excess of some halogenated derivatives, such as advanced oxygenation protein products (AOPP), has been detected in the CSF and serum. «Accelerated self-halogenation» and increased levels of haloperoxidases and AOPP proteins indicate that halogenative stress is present in Parkinson's disease. In addition, 3-iodo-L-tyrosine, a halogenated derivative, shows «parkinsonian» toxicity in experimental models, since it has been observed to induce α-synuclein aggregation and damage to dopaminergic neurons in the mouse brain and intestine. The hypothesis is that patients with Parkinson's disease display halogenative stress related to a haloenzymatic alteration of the synthesis or degradation of oxyacid of halogens and their halogenated derivatives. This halogenative stress would be related to nervous system damage.

Vanadium haloperoxidases play an important catalytic role in the natural production of antibiotics which are difficult to make in the laboratory. Understanding the catalytic mechanism of these enzymes will aid in the production of artificial enzymes useful in bioengineering the synthesis of drugs and useful chemicals. However, the catalytic mechanism remains not fully understood yet. In this paper, we investigate one of the key steps of the catalytic mechanism using QM/MM. Our investigation reveals a new N-halohistidyl intermediate in the catalytic cycle of vanadium chloroperoxidase (VCPO). This new intermediate, in turn, can explain the known inhibition of the enzyme by substrate under acidic conditions (pH < 4). Additionally, we examine the possibility of replacing V in VCPO by Nb or Ta using QM modeling. We report the new result that the Gibbs free energy barriers of several steps of the catalytic cycle are lower in the case of artificial enzymes, incorporating NbO 4 3 − or TaO 4 3 − instead of VO 4 3 − . Our results suggest that these new artificial enzymes may catalyze the oxidation of halide faster than the natural enzyme. The catalytic mechanism of vanadium chloroperoxidase is investigated using QM/MM, and evidence for a new N-halohistidyl intermediate is found in the last step of mechanism. When V is replaced with Nb or Ta, the barrier heights in the mechanism are calculated to be lower for some steps, using a QM model. Thus, we suggest that replacement of V with Nb or Ta may lead to an artificial enzyme with a faster rate of catalysis. [ABSTRACT FROM AUTHOR]

Defective bismuth telluride (Bi 2 Te 3 ) nanosheets, an artificial nanozyme mimicking haloperoxidase activity (hPOD), show promise as eco-friendly, bactericidal, and antimicrofouling materials by enhancing cytotoxic hypohalous acid production from halides and H 2 O 2 . Microscopic and spectroscopic characterization reveals that controlled NaOH (upto X = 250 µL) etching of the nearly inactive non-transition metal chalcogenide Bi 2 Te 3 nanosheets creates controlled defects (d), such as Bi 3+ species, in d-Bi 2 Te 3 -X that induces enhanced hPOD activity. d-Bi 2 Te 3 -250 exhibits approximately eight-fold improved hPOD than the as-grown Bi 2 Te 3 nanosheets. The antibacterial activity of d-Bi 2 Te 3 -250 nanozymes, studied by bacterial viability, show 1, and 45% viability for Staphylococcus aureus and Pseudomonas aeruginosa, respectively, prevalent in marine environments. The hPOD mechanism is confirmed using scavengers, implicating HOBr and singlet oxygen for the effect. The antimicrofouling property of the d-Bi 2 Te 3 -250 nanozyme has been studied on Pseudomonas aeruginosa biofilm in a lab setting by multiple assays, and also on titanium (Ti) plates coated with the nanozyme mixed commercial paint, exposed to seawater in a real setting. All studies, including direct microscopic evidence, exhibit inhibition of microfouling, up to ≈73%, in the presence of nanozymes. This approach showcases that defect engineering can induce antibacterial, and antimicrofouling activity in non-transition metal chalcogenides, offering an inexpensive alternative to noble metals., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Abstract Vanadate‐dependent chloroperoxidase from Curvularia inaequalis catalyzes 5‐endo‐trig bromocyclizations of α‐allenols to produce valuable halofunctionalized furans as versatile synthetic building blocks. In contrast to other haloperoxidases, also the more challenging 5‐exo‐trig halocyclizations of γ‐allenols succeed with this system even though the scope still remains more narrow. Benefitting from the vanadate chloroperoxidase‘s high resiliency towards oxidative conditions, cyclization‐inducing reactive hypohalite species are generated in situ from bromide salts and hydrogen peroxide. Crucial requirements for high conversions are aqueous biphasic emulsions as reaction media, stabilized by either cationic or non‐ionic surfactants.

Vanadate‐dependent chloroperoxidase from Curvularia inaequalis catalyzes 5‐endo‐trig bromocyclizations of α‐allenols to produce valuable halofunctionalized furans as versatile synthetic building blocks. In contrast to other haloperoxidases, also the more challenging 5‐exo‐trig halocyclizations of γ‐allenols succeed with this system even though the scope still remains more narrow. Benefitting from the vanadate chloroperoxidase's high resiliency towards oxidative conditions, cyclization‐inducing reactive hypohalite species are generated in situ from bromide salts and hydrogen peroxide. Crucial requirements for high conversions are aqueous biphasic emulsions as reaction media, stabilized by either cationic or non‐ionic surfactants. [ABSTRACT FROM AUTHOR]

Vanadium-dependent haloperoxidases (V-HPO) are specific enzymes involved in the metabolism of reactive oxygen species in marine algae. These enzymes contribute to early embryogenesis of algae in the order Fucales, catalyzing the reactions which result in phlorotannin incorporation into the newly forming zygote cell wall and adhesive material. In this study we showed that early embryogenesis in Fucus vesiculosus is accompanied by synchronous changes of V-HPO activity, hydrogen peroxide content and content of cell-wall-associated phlorotannins. Phlorotannin incorporation into the cell wall of Fucus zygotes had already begun 1 h after fertilization, and this process was accompanied by rapid increase of H2O2 content and V-HPO activity. We suggest that altogether this initiates polymerization of phenolics and their cross-linking with the major cell wall constituent, alginic acid. Presumably, de novo phlorotannin biosynthesis is involved in this process, as GC-MS analysis showed dramatic changes in content of intracellular phloroglucinol and low-molecular-weight phlorotannins during the first 9 days of F. vesiculosus embryogenesis. [ABSTRACT FROM AUTHOR]

Halide assays are important for the study of enzymatic dehalogenation, a topic of great industrial and scientific importance. Here we describe the development of a very sensitive halide assay that can detect less than a picomole of bromide ions, making it very useful for quantifying enzymatic dehalogenation products. Halides are oxidised under mild conditions using the vanadium‐dependent chloroperoxidase from Curvularia inaequalis, forming hypohalous acids that are detected using aminophenyl fluorescein. The assay is up to three orders of magnitude more sensitive than currently available alternatives, with detection limits of 20 nM for bromide and 1 μM for chloride and iodide. We demonstrate that the assay can be used to determine specific activities of dehalogenases and validate this by comparison to a well‐established GC‐MS method. This new assay will facilitate the identification and characterisation of novel dehalogenases and may also be of interest to those studying other halide‐producing enzymes. [ABSTRACT FROM AUTHOR]

Common peroxidase action and haloperoxidase action are quantifiable as light emission from dioxygenation of luminol (5-amino-2,3-dihydrophthalazine-1,4-dione). The velocity of enzyme action is dependent on the concentration of reactants. Thus, the reaction order of each participant reactant in luminol luminescence was determined. Horseradish peroxidase (HRP)-catalyzed luminol luminescence is first order for hydrogen peroxide (H2O2), but myeloperoxidase (MPO) and eosinophil peroxidase (EPO) are second order for H2O2. For MPO, reaction is first order for chloride (Cl−) or bromide (Br−). For EPO, reaction is first order for Br−. HRP action has no halide requirement. For MPO and EPO, reaction is first order for luminol, but for HRP, reaction is greater than first order for luminol. Haloperoxidase-catalyzed luminol luminescence requires acidity, but HRP action requires alkalinity. Unlike the radical mechanism of common peroxidase, haloperoxidases (XPO) catalyze non-radical oxidation of halide to hypohalite. That reaction is second order for H2O2 is consistent with the non-enzymatic reaction of hypohalite with a second H2O2 to produce singlet molecular oxygen (1O2*) for luminol dioxygenation. Alternatively, luminol dehydrogenation by hypohalite followed by reaction with H2O2 yields dioxygenation consistent with the same reaction order. Haloperoxidase action, Cl−, and Br− are specifically quantifiable as luminol luminescence in an acidic milieu.

Many marine natural products and enzymes have important medical applications in the pharmaceutical, diagnostic and biotechnological industries. These compounds and enzymes are at various stages of development, ranging from evaluation of their biological activities, to testing in clinical trials, and to their incorporation into commercial products. Notwithstanding this success, the rise in drug-resistant infections demands new drugs and strategies for eradication or control of invading pathogenic organisms. In addition, early disease detection requires new or more sensitive biochemical diagnostic tools. Solutions to these problems can be provided through discovery of new bioactive compounds, studies of their biogenesis, including endogenous biosynthetic enzyme investigations, and elucidation of their molecular mechanisms of action. Such strategies will allow chemists and pharmacologists, working in a collaborative effort, to pursue the development of novel drugs and diagnostics.

Ruminant livestock produce around 24% of global anthropogenic methane emissions. Methanogenesis in the animal rumen is significantly inhibited by bromoform, which is abundant in seaweeds of the genus Asparagopsis . This has prompted the development of livestock feed additives based on Asparagopsis to mitigate methane emissions, although this approach alone is unlikely to satisfy global demand. Here we engineer a non-native biosynthesis pathway to produce bromoform in vivo with yeast as an alternative biological source that may enable sustainable, scalable production of bromoform by fermentation. β-dicarbonyl compounds with low p K a values were identified as essential substrates for bromoform production and enabled bromoform synthesis in engineered Saccharomyces cerevisiae expressing a vanadate-dependent haloperoxidase gene. In addition to providing a potential route to the sustainable biological production of bromoform at scale, this work advances the development of novel microbial biosynthetic pathways for halogenation.

Recent developments in enzymatic bleaching processes have led to replacement strategies of harsh chemicals by haloperoxidases. For this purpose, it is important to control the haloperoxidase-mediated formation of adsorbable organic halides (AOX). In this study, we studied the chlorination of monomeric and dimeric lignin model substrates. Guaiacol, acetovanillone, veratryl alcohol, pinoresinol and adlerol were treated with Curvularia verruculosa haloperoxidase and compared to a sodium hypochlorite treatment. High-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS) analysis was employed for the characterization of the reaction products. Our results show that while treatment with haloperoxidases in the presence of sodium chloride and hydrogen peroxide leads to no improvement in AOX formation compared to chemical treatment with NaOCl, addition of ammonium chloride substantially lessens chlorination and promotes β-O-4 ether bond cleavage. The use of ammonium chloride in conjunction with enzymatic haloperoxidase-based bleaching could be a route to minimize lignin chlorination. [ABSTRACT FROM AUTHOR]

Among planktonic communities haloperoxidase enzymes may play a role in the control of intracellular and extracellular reactive oxygen species, in the generation of halogenated organic compounds and in chemical interactions between microbes. We introduce a sensitive fluorometric assay with a large dynamic range that is based on the dearylation of aminophenyl fluorescein (APF) to fluorescein by highly reactive oxygen species. Bromoperoxidase and chloroperoxidase enzymes catalyze the reaction between hydrogen peroxide and halides to generate highly reactive hypohalite intermediates able to dearylate APF. The fundamentals and standardization of the approach are illustrated using a partially purified, vanadium-dependent bromoperoxidase from the red seaweed Corallina officinalis. Laboratory cultures of two polar diatoms, Porosira glacialis and Fragilariopsis cylindrus, are used to illustrate the sensitivity and potential applications of the approach for in vitro, in vivo and in situ measurements of bromoperoxidase activity. These two diatoms differ in biovolume-specific bromoperoxidase activity by 2-orders of magnitude, from 5.4 to 0.044 fmol fluorescein μm-3 h-1, respectively. The approach is also used to investigate the partition of haloperoxidase activity between different size fractions of summer coastal planktonic communities, illustrating that generally more than 50% of the haloperoxidase activity occurred in a >10 μm size fraction that was dominated by diatoms. The assay has the potential to be of value in many aspects of haloperoxidase research, including developing an improved understanding of the roles of haloperoxidase enzymes in microbial planktonic communities.

Vanadium-dependent haloperoxidases are a class of enzymes that catalyze oxidation reactions with halides to form halogenated organic products and water. These enzymes include chloroperoxidase and bromoperoxidase, which have very different protein sequences and sizes, but regardless the coordination environment of the active sites is surprisingly constant. In this manuscript, the comparison of the coordination chemistry of V-containing-haloperoxidases of the trigonal bipyramidal geometry was done by data mining. The catalytic cycle imposes changes in the coordination geometry of the vanadium to accommodate the peroxidovanadium(V) intermediate in an environment we describe as a distorted square pyramidal geometry. During the catalytic cycle, this intermediate converts to a trigonal bipyramidal intermediate before losing the halogen and forming a tetrahedral vanadium-protein intermediate. Importantly, the catalysis is facilitated by a proton-relay system supplied by the second sphere coordination environment and the changes in the coordination environment of the vanadium(V) making this process unique among protein catalyzed processes. The analysis of the coordination chemistry shows that the active site is very tightly regulated with only minor changes in the coordination geometry. The coordination geometry in the protein structures deviates from that found for both small molecules crystalized in the absence of protein and the reported functional small molecule model compounds. At this time there are no examples reported of a structurally similar small molecule with the geometry observed for the peroxidovanadium(V) in the active site of the vanadium-containing haloperoxidases. [ABSTRACT FROM AUTHOR]

Cover Feature: Erythronium Bonds: Noncovalent Interactions Involving Group 5 Elements as Electron-Density Acceptors (Chem. Eur. J. 60/2023) Cambridge Structural Database, haloperoxidase, noncovalent interactions, sigma-hole interactions, vanadium Keywords: Cambridge Structural Database; haloperoxidase; noncovalent interactions; sigma-hole interactions; vanadium EN Cambridge Structural Database haloperoxidase noncovalent interactions sigma-hole interactions vanadium 1 1 1 10/31/23 20231026 NES 231026 B Vanadium(V) derivatives b , and to a lesser extent analogous compounds of niobium and tantalum, form attractive interactions with electron-rich atoms (neutral or anionic). [Extracted from the article]

Halogens can be very important for active agents as vital parts of their binding mode, on the one hand, but are on the other hand instrumental in the synthesis of most active agents. However, the primary halogenating compound is molecular chlorine which has two major drawbacks, high energy consumption and hazardous handling. Nature bypassed molecular halogens and evolved at least six halogenating enzymes: Three kind of haloperoxidases, flavin-dependent halogenases as well as α-ketoglutarate and S-adenosylmethionine (SAM)-dependent halogenases. This review shows what is known today on these enzymes in terms of biocatalytic usage. The reader may understand this review as a plea for the usage of halogenating enzymes for fine chemical syntheses, but there are many steps to take until halogenating enzymes are reliable, flexible, and sustainable catalysts for halogenation.

Meroterpenoid natural products are important bioactive molecules with broad distribution throughout nature. In Streptomyces bacteria, naphthoquinone-based meroterpenoids comprise a simple yet structurally fascinating group of natural product antibiotics that are enzymatically constructed through a series of asymmetric alkene and arene halofunctionalization reactions. This account article highlights our discovery and characterization of a group of vanadium-dependent chloroperoxidase enzymes that catalyze halogen-assisted cyclization and rearrangement reactions and have inspired biomimetic syntheses of numerous meroterpenoid natural products. 1 Introduction 2 Early Biosynthetic Insights and the Characterization of Alkene Halofunctionalization in Napyradiomycin Biosynthesis 3 Discovery of the Merochlorin Natural Products and Enzymatic Aryl Halofunctionalization 4 Discovery and Development of Unifying THN-Based Meroterpenoid Biosynthesis and Synthesis Approaches 5 Insights into Naphterpin and Marinone Biosynthesis Involving Cryptic Aryl Halofunctionalization Reactions 6 Closing Thoughts [ABSTRACT FROM AUTHOR]

Diatoms are known to produce a variety of halogenated compounds, which were recently shown to have a role in allelopathic interactions between competing species. The production of these compounds is linked to haloperoxidase activity. This research, has shown that this system may also be involved in diatom-bacteria interactions via the H2O2 dependent inactivation of a type of quorum sensing (QS) molecule, i.e., N-β-ketoacylated homoserine lactones (AHLs), by a natural haloperoxidase system from the benthic diatom Nitzschia cf pellucida. The AHL degradation pathway towards corresponding halogenated derivatives was elucidated via HPLC-MS analysis and the synthesis of a broad series of novel halogenated AHL analogues as reference compounds. Furthermore, their biological activity as quorum sensing modulators was directly compared and evaluated against a series of naturally occurring β-keto-AHLs. It has been demonstrated that the loss of the QS activity results from the final cleavage of the halogenated N-acyl chain of the signal molecules.

Despite its paramount role in the functioning of coastal ecosystems, relatively little is known about halogen metabolism in giant kelp ( Macrocystis pyrifera ). This is an important shortcoming given the potential implications for marine and atmospheric chemical processes in the wide distribution range of Macrocystis . The work presented here constitutes the first in depth investigation of the uptake, efflux, and of the physiological function of iodide in this important kelp species. Iodide uptake and efflux rates were measured in adult sporophytes of Macrocystis under normal and stressed (exogenous hydrogen peroxide and an elicitor-triggered oxidative burst) conditions. Kelp tissue took up iodide according to Michaelis-Menten type kinetics when incubated in seawater enriched with various concentrations of iodide. Upon the addition of exogenous hydrogen peroxide, simulating oxidative stress, a marked efflux of iodide occurred. In situ generation of hydrogen peroxide was elicited in Macrocystis upon the addition of oligomeric degradation products of alginate as well as arachidonic acid and methyl jasmonate constituting a defensive oxidative burst that could be linked to iodine accumulation. H 2 O 2 was detected at the single cell level using dichlorohydrofluorescein diacetate, a fluorogenic probe capable of detecting intracellular H 2 O 2 . When assayed for vanadium haloperoxidase activity, several bromoperoxidase isoforms were detected as well as a single iodoperoxidase. Altogether, the results of this study show that Macrocystis has an elaborate iodine metabolism, which is likely significant for impacting iodine speciation in seawater around kelp beds and for volatile halogen emissions into the coastal atmosphere. [ABSTRACT FROM AUTHOR]

Phytases are valuable industrial enzymes widely used in food and feed production for monogastric animals. The purpose of this research is to study the possibility of employing solid-state fermentation (SSF) for phytase production by Aspergillus oryzae SBS50 using mixed substrates. Medium components for improvement of phytase production were optimized using 'one variable at a time' method. Optimization resulted in an overall 2.1 times increase in phytase production (506.12 U/g DMR) at 30 °C, pH 5.0 and moisture ratio of 1:4 supplemented with 0.75% ammonium sulphate. There was reduction in phytase production with reduction in water activity. The phytic acid was extracted from flours using hydrochloric acid (HCl) and trichloroacetic acid (TCA). Higher phytic acid content was extracted from wheat flour (3881.6 μg/g), among all the tested flours by HCl extraction method. Fungal phytase was used in the dephytinization of flours. Phytase supplementation enhanced the release of inorganic phosphate, reducing sugars and soluble proteins from all the flours. Treatment of different cereal flours with Aspergillus oryzae phytase resulted in 90–97% reduction in phytic acid content after 24h. A significant amount of inorganic phosphorus was released from wheat flour (10.42 mg/g), pearl millet flour (9.1 mg/g) followed by gram flour (6.2 mg/g) and rice flour (3.9 mg/g). The addition of vanadium resulted in the catalytic conversion of phytase into haloperoxidase, as well as the suppression of phytase activity. This study revealed that phytase from A. oryzae SBS50 can be utilized to improve the nutritional content of cereal-based meals and food products in the food processing sectors. Furthermore, semisynthetic haloperoxidase could be useful in various biotechnological applications. • Estimation of phytic acid in commonly used food ingredients. • Enzymatic reduction of anti-nutritional factor using phytase. • Conversion of phytase into vanadium-dependent haloperoxidase. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bacterial peroxidases belong to the widespread CCP_MauG family. • Bacterial peroxidases are divided into classical and non-classical enzymes. • The active P heme has a OH–/His HS coordination in a HS/LS thermal equilibrium. • Activation and catalytic mechanism are reviewed. • Non-classical YhjA structural model shows the architecture of this tri-hemic enzyme. Bacterial peroxidases are responsible for the reduction of hydrogen peroxide to water. Found in the periplasm of gram-negative bacteria, they are one of the defense mechanisms against endogenous and exogenous peroxide stress under low oxygen tensions. Besides being involved in peroxide detoxification, bacterial peroxidases have been proposed to constitute an alternative pathway to the respiratory chain under anoxic conditions, as demonstrated in E. coli that can use hydrogen peroxide as an electron acceptor in the absence of oxygen. Bacterial peroxidases are c -type cytochromes with either two or three c -type hemes bound to the polypeptide chain, being divided into classical or non-classical, respectively. Orthologous to the classical bacterial peroxidases are the MauG enzymes that share some structural, spectroscopic and sequence similarities but have distinct physiological roles (though for most their function remains unknown). The spectroscopic and kinetic data on bacterial peroxidases are reviewed for both classes. Most classical bacterial peroxidases require reductive activation that consists in structural changes so that the catalytic heme becomes accessible to the substrate. However, non-classical enzymes are ready to bind the hydrogen peroxide as their catalytic center is penta-coordinated, which is also observed in their structural model. The few studies that report the involvement of bacterial peroxidases from pathogenic bacteria in biofilms, is an indication that these enzymes might contribute to their infection mechanism and thus can constitute alternative drug targets. [ABSTRACT FROM AUTHOR]

Cerium oxide (CeO 2), with haloperoxidase mimic activity, has attracted attention because it can break through many limitations of biological enzymes as a green and efficient antibacterial agent. However, low Ce3+ concentration in CeO 2 restricts the activities of haloperoxidase mimicry, which hinders its application. Here, CeO 2 was loaded onto carbon nanotubes (CNTs), where dopamine hydrochloride (DA) was polymerized as the "linker" and CNTs the "skeleton." Two types of samples, termed CeO 2 -CNT (CeO 2 49@PDA/CNT and CeO 2 77@PDA/CNT), were prepared and CeO 2 was found to be uniformly distributed on CNTs, and their Ce3+ and oxygen (O) vacancy concentrations analyzed. CeO 2 77@PDA/CNT, with the higher Ce3+ and O vacancy concentration, showed excellent antibacterial performance, up to 98.03%. This study demonstrated a method for enhancing the activities of haloperoxidase mimicry and antibacterial performance of CeO 2 with CNTs as the skeleton. • CNT loaded CeO 2 NPs, CeO 2 -CNT composite material were prepared. • CeO 2 -CNT could mimic natural haloperoxidase, which breaked through the limitation of natural biological enzymes. • CeO 2 -CNT had stronger activity of haloperoxidase mimicry and antibacterial performance than CeO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • The transformation of mineralized vanadium into bioavailable H 2 VO 4 -/VO2+ is addressed. • Vanadium is an essential factor in nitrogen fixation, algal haloperoxidases, fan worms and ascidians. • The role of vanadium in medicinal applications is covered. • Vanadium exhibits promising potentiality in the treatment of diabetes, carcinoma and bacterial infections. The present review covers the environmental availability of vanadium and vanadium's impact on the life sphere (geo-sphere, atmosphere, marine environments), as well as its potentiality in the treatment of diseases such as cancer, diabetes and bacterial infections. In particular, the following topics are addressed: (1) vanadium in marine environments (halide oxidation by haloperoxidases in the seaweed Ascophyllum nodosum and by marine bacteria associated with macroalgae; accumulation and redox transformation of vanadium by ascidians and fan worms); (2) the role of vanadium in nitrogen fixation by diazotrophs in the root nodules of legumes, and in liverworts and hornwarts; (3) amavadin in the fly agaric mushroom; (4) vanadium speciation by unicellular organisms (bacteria, protozoa) and adjunctive medicinal applications; (5) the potentiality of vanadium (coordination compounds) in the treatment of diseases such as cancer and diabetes, and bacterial infections. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of a novel adsorbent with antibacterial properties. • Ce-MOF loading can greatly improve the adsorption capacity of fibers for 2,4-D. • The haloperoxidase activity of Ce-MOF can give the fiber excellent antibacterial activity. • Ce-MOF@ABP is easier to recycle than powdered Ce-MOF. • Ce-MOF@ABP can be used as a filtration membrane to purify organic wastewater. 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the most widely used herbicides with strong environmental toxicity, and it is necessary to be removed from water. However, some traditional adsorbents may be contaminated by bacteria during the removal process, which will affect the adsorption performance. Therefore, a novel adsorbent (Ce-MOF@ABP) with antibacterial properties was developed for the removal of 2,4-D. The adsorbent is prepared by in-situ growth of Ce-based MOF with UiO-66 structure on the surface of electrospun nanofibers by solvothermal method. The results of static adsorption experiments show that the composite fibrous membrane has a good removal effect on 2,4-D. The adsorption process is more consistent with the pseudo-second-order model and Langmuir model. The theoretical maximum adsorption capacity is 200.80 mg/g. The dynamic filtration experiment also shows a removal rate of 90.3% within 6 min (the membrane thickness is 0.12 mm). And most importantly, the haloperoxidase activity of Ce-MOF could endows fibrous membrane with excellent antibacterial properties, and the bacteriostatic rate of Escherichia coli is 92.91%. This study provides an innovative idea for the development of adsorbents/membranes with organic contaminant removal and antibacterial capabilities. [ABSTRACT FROM AUTHOR]

The codon-optimized phytase gene of the thermophilic mold Sporotrichum thermophile ( St- Phy) was expressed in Pichia pastoris. The recombinant P. pastoris harboring the phytase gene ( rSt- Phy) yielded a high titer of extracellular phytase (480 ± 23 U/mL) on induction with methanol. The recombinant phytase production was ~40-fold higher than that of the native fungal strain. The purified recombinant phytase (rSt-Phy) has the molecular mass of 70 kDa on SDS-PAGE, with K and V (calcium phytate), k and k/ K values of 0.147 mM and 183 nmol/mg s, 1.3 × 10/s and 8.84 × 10/M s, respectively. Mg and Ba display a slight stimulatory effect, while other cations tested exert inhibitory action on phytase. The enzyme is inhibited by chaotropic agents (guanidinium hydrochloride, potassium iodide, and urea), Woodward's reagent K and 2,3-bunatedione, but resistant to both pepsin and trypsin. The rSt-Phy is useful in the dephytinization of broiler feeds efficiently in simulated gut conditions of chick leading to the liberation of soluble inorganic phosphate with concomitant mitigation in antinutrient effects of phytates. The addition of vanadate makes it a potential candidate for generating haloperoxidase, which has several applications. [ABSTRACT FROM AUTHOR]

The phytase of the yeast Pichia anomala is a histidine acid phosphatase based on signature sequences and catalytic amino acids identified by site-directed mutagenesis. Among modulators, N-bromosuccinimide and butanedione inhibit phytase, while Ca and Ni stimulate slightly. Vanadate exhibits competitive inhibition of phytase, making it bifunctional to act as haloperoxidase. Molecular docking supports vanadate to share its binding site with phytate. The T, activation energy ( E), temperature quotient ( Q), activation energy of thermal inactivation (E), and enthalpy (ΔH) of the enzyme are 4.0 min (80 °C), 27.72 kJ mol, 2.1, 410.62 kJ mol, and ∼407.8 kJ mol (65-80 °C), respectively. The free energy of the process (ΔG) increases from 49.56 to 71.58 kJ mol with rise in temperature, while entropy of inactivation (ΔS) remains constant at ∼1.36 kJ mol K. The supplementation of whole wheat dough with rPPHY resulted in 72.5 % reduction in phytic acid content of bread. These characteristics confirm that the phytase has adequate thermostability for its applicability as a food and feed additive. [ABSTRACT FROM AUTHOR]

Haloperoxidases are useful oxygenases involved in halogenation of a range of water-insoluble organic compounds and can be used without additional high-cost cofactors. In particular, organic solvent-stable haloperoxidases are desirable for enzymatic halogenations in the presence of organic solvents. In this study, we adopted a directed evolution approach by error-prone polymerase chain reaction to improve the organic solvent-stability of the homodimeric BPO-A1 haloperoxidase from Streptomyces aureofaciens. Among 1,000 mutant BPO-A1 haloperoxidases, an organic solvent-stable mutant OST48 with P123L and P241A mutations and a high active mutant OST959 with H53Y and G162R mutations were selected. The residual activity of mutant OST48 after incubation in 40% (v/v) 1-propanol for 1 h was 1.8-fold higher than that of wild-type BPO-A1. In addition, the OST48 mutant showed higher stability in methanol, ethanol, dimethyl sulfoxide, and N,N-dimethylformamide than wild-type BPO-A1 haloperoxidase. Moreover, after incubation at 80°C for 1 h, the residual activity of mutant OST959 was 4.6-fold higher than that of wild-type BPO-A1. Based on the evaluation of single amino acid-substituted mutant models, stabilization of the hydrophobic core derived from P123L mutation and increased numbers of hydrogen bonds derived from G162R mutation led to higher organic solvent-stability and thermostability, respectively. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:917-924, 2015 [ABSTRACT FROM AUTHOR]

Haloperoxidases are oxygenases that catalyze the halogenation of a range of organic compounds without the need for additional high-cost cofactors. Thus, haloperoxidases with high activity and stability are desired for industrial application. In this study, a directed evolution approach was adopted to improve the thermostability of the homodimeric BPO-A1 haloperoxidase from Streptomyces aureofaciens . Among 1000 mutant BPO-A1 haloperoxidases, 2 mutants HT177 and HT507, having higher thermostabilities than the wild-type BPO-A1 haloperoxidase, were obtained by directed evolution. The residual activities of mutants HT177 and HT507 were 2.3- and 5.1-fold higher than that of wild-type BPO-A1, respectively, after incubation at 80 °C for 1 h. In addition, mutant HT177 showed higher stability in organic solvents, such as methanol, ethanol, dimethyl sulfoxide, and N , N -dimethylformamide, than the wild-type BPO-A1 haloperoxidase. Furthermore, mutant HT507 showed higher specific activity. Based on the evaluation of single-amino-acid-substituted mutants, stabilization of the α-helix conformation, substitution of amino acid residues located at the surface of the protein molecule, and enhancement of the interaction between subunits may account for the improvement in thermostability, organic solvent stability, and specific activity. Consequently, the thermostability, organic solvent stability, and specific activity of S. aureofaciens BPO-A1 haloperoxidase were successfully improved by a directed evolution approach. [ABSTRACT FROM AUTHOR]