Previously, Lipase A from Bacillus subtilis was subjected to in vitro directed evolution using iterative saturation mutagenesis, with randomization sites chosen on the basis of the highest B-factors available from the crystal structure of the wild-type enzyme. This provided mutants that, unlike wild-type enzyme, retained a large part of their ...

To unveil the metabolic impact of tellurite in the bacterial cell, the effect of this toxicant on the expression and activity of key enzymes of the Escherichia coli glycolytic pathway was analyzed. E. coli exposure to tellurite results in: (i) increased glucose consumption, which was paralleled by an increased expression ...

The performance of immobilized enzyme systems is often limited by cofactor diffusion and regeneration. Here, we demonstrate an engineered enzyme capable of utilizing the minimal cofactor nicotinamide mononucleotide (NMN(+)) to address these limitations. Significant gains in performance are observed with NMN(+) in immobilized systems, despite a decreased turnover rate with ...

β-d-Galactosidase (BGAL) from Kluyveromyces lactis was covalently immobilized to functionalized silicon dioxide nanoparticles (10-20nm). The binding of the enzyme to the nanoparticles was confirmed by Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Functionalized nanoparticles showed 87% immobilization yield. Soluble and immobilized enzyme preparation exhibited pH-optima at pH 6.5 ...

Recombinant human β-mannosidase (rhMANB) is an important glycosidase enzyme that degrades mannose-linked glycoproteins and mannan polysaccharides. rhMANB was purified and covalently immobilized onto magnetic nanoparticles. The immobilization of the enzyme was confirmed by Fourier-transform infrared spectroscopy (FTIR) and magnetic nanoparticles linked immunosorbent assay (MagLISA). Antibodies against rhMANB were raised, purified ...

Recombinant S-adenosylhomocysteine hydrolase from Corynebacterium glutamicum (CgSAHase) was covalently bound to Eupergit® C. The maximum yield of bound protein was 91% and the catalytic efficiency was 96.9%. When the kinetic results for the immobilized enzyme were compared with those for the soluble enzyme, no decrease in the catalytic efficiency of ...

An effective carrier matrix for diastase alpha amylase immobilization has been fabricated by gum acacia-gelatin dual templated polymerization of tetramethoxysilane. Silver nanoparticle (AgNp) doping to this hybrid could significantly enhance the shelf life of the impregnated enzyme while retaining its full bio-catalytic activity. The doped nanohybrid has been characterized as ...

Deactivation extents of cellobiohydrolase, endoglucanase, and a total cellulase mixture (Spezyme CP) were studied independently as functions of incubating time and mixing intensity. It was found that the decrease in total cellulase activity was more strongly related to deactivation of cellobiohydrolase 1 (CBH1) than endoglucanase. The mass-averaged shear in orbiting ...

Polyacrylonitrile nanofibrous membranes (PANNFM) were prepared by electrospinning from 10wt.% of PAN solution and its surface was modified by amidination reaction. A new chitosan degrading enzyme from Aspergillus sp. was covalently immobilized on PANNFM. Immobilization efficiency of 80% was achieved by activating PANNFM surface for 30min followed by 2h treatment ...

Tyrosinase was immobilized on glutaraldehyde crosslinked chitosan-clay composite beads and used for phenol removal. Immobilization yield, loading efficiency and activity of tyrosinase immobilized beads were found as 67%, 25% and 1400U/g beads respectively. Optimum pH of the free and immobilized enzyme was found as pH 7.0. Optimum temperature of the ...

Biotechnology also holds tremendous opportunities for realizing functional polymeric materials. Biocatalytic pathways to polymeric materials are an emerging research area with not only enormous scientific and technological promise, but also a tremendous impact on environmental issues. Many of the enzymatic polymerizations reported proceed in organic solvents. However, enzymes mostly show ...

Seven mammalian sirtuins are nicotinamide adenine dinucleotide (NAD)(+)-dependent deacetylases and are important modulators of energy metabolism and stress resistance. Two new studies by Du et al. (2011) and Peng et al. (2011) identify a new enzymatic activity for SIRT5, expanding the cellular repertoire of posttranslational modifications targeted by the sirtuins.

Biodiesel has attracted more and more attention in recent years because of its biodegradability, environmentally friendliness, and renewability. Contrary to the conventional chemical catalysis method to produce biodiesel, the biochemical catalysis method developed quickly in the past decade and many immobilized enzymes are commercially available to meet the large-scale industrialization ...

In this study we report the use of functionalized carbon-based nanomaterials, such as amine-functionalized graphene oxide (GO) and multi-walled carbon nanotubes (CNTs), as effective immobilization supports for various lipases and esterases of industrial interest. Structural and biochemical characterization have revealed that the curvature of the nanomaterial affect the immobilization yield, ...

We have previously demonstrated that the two Exonuclease III (Xth) family members present within the obligate human pathogen Neisseria meningitidis, NApe and NExo, are important for survival under conditions of oxidative stress. Of these, only NApe possesses AP endonuclease activity, while the primary function of NExo remained unclear. We now ...

The continuous enzymatic conversion of D: -galactose to D: -tagatose with an immobilized thermostable L: -arabinose isomerase in packed-bed reactor and a novel method for D: -tagatose purification were studied. L: -arabinose isomerase from Thermoanaerobacter mathranii (TMAI) was recombinantly overexpressed and immobilized in calcium alginate. The effects of pH and ...

This work reviews the stripping off, role of water molecules in activity, and flexibility of immobilized Candida antarctica lipase B (CALB). Employment of CALB in ring opening polyester synthesis emphasizing on a polylactide is discussed in detail. Execution of enzymes in place of inorganic catalysts is the most green alternative ...

Aquatic organisms are constantly exposed to both physical (e.g. temperature and salinity variations) and chemical (e.g. endocrine disruptor chemicals, heavy metals, hydrocarbons, diatom toxins, and other toxicants) stressors which they react to by activating a series of defense mechanisms. This paper reviews the literature on the defense systems, including detoxification ...

Okadaic acid (OA), a lipophilic toxin, is produced by Dinophysis and Prorocentrum, and causes diarrheic shellfish poisoning to humans. The mechanism of OA action is based on the reversible inhibition of protein phosphatase type 2A (PP2A) by the toxin. Therefore, this inhibition could be used to develop assay for OA ...

Highly stable enzyme coaggregates were developed using amyloid fibrils as support materials. Amyloid fibril formation was induced by ionic liquids, and immobilization was done by the coaggregation of enzymes and amyloid fibrils followed by chemical cross-linking. Transmission and scanning electron microscopy studies were carried out to characterize the coaggregates. The ...

Agitation speed was found to influence the tannase production and fungal growth of Aspergillus niger FETL FT3. The optimal agitation speed was at 200 rpm which produced 1.41 U/ml tannase and 3.75 g/l of fungal growth. Lower or higher agitation speeds than 200 rpm produced lower enzyme production and fungal growth. Based on the ...

Abstract: Pectinesterase isolated from Malatya apricot pulp was noncovalently and covalently immobilized onto bentonite and glutaraldehyde-containing amino group functionalized porous glass beads surface at pH 8.0 and pH 9.0, respectively. The effect of various parameters such as pH, temperature, activation energy, heat and storage stability on immobilized enzyme were investigated. ...

Byssus threads are tough biopolymer produced by mussels (Mytilus viridis) to attach themselves to rocks. These were collected from mussels in their natural habitat (N) and from animals maintained in laboratory condition (L) as a novel support. Byssus thread surfaces were characterized by SEM analysis, chemically modified and used for ...

O-Pentynyl dextran (PyD), an amphiphilic polysaccharide derivative with a degree of substitution (DS) of 0.43 was compared with ion exchange resins Lewatit VP OC 1600, Amberlite XAD 761 and Duolite A568 for immobilization of Lipase from Rhizopus arrhizus by adsorption method. The immobilized enzymes were employed for esterification of octanoic acid ...

Several new types of carriers and technologies have been implemented in the recent past to improve traditional enzyme immobilization which aimed to enhance enzyme loading, activity and stability to decrease the enzyme biocatalyst cost in industrial biotechnology. These include cross-linked enzyme aggregates, microwave-assisted immobilization, click chemistry technology, mesoporous supports and ...

Immobilization of enzymes on the transducer surface is a necessary and critical step in the design of biosensors. An overview of the different immobilization techniques reported in the literature is given, dealing with classical adsorption, covalent bonds, entrapment, cross-linking or affinity as well as combination of them and focusing on ...

Salivary alpha-Amylase (sAA) is a starch digesting enzyme. In addition to its function in the context of nutrition, sAA has also turned out to be useful for monitoring sympathetic nervous system activity. Recent studies on humans have found a relationship between intra-individual changes in sAA activity and physical and psychological ...

Lipase from Pseudomonas stutzeri PL-836 was immobilized on hydrophobic supports and evaluated in the transesterification of wood sterols in solvent-free and solvent-containing media. Triton X-100 was used as additive during immobilization in butyl and octadecyl sepabeads increasing enzyme activity yield by 5% and 60%, respectively. Hyperactivation was observed during immobilization ...

Using 0.2% glutaraldehyde as the cross-linker, lysozyme was covalently immobilized onto electrospun polystyrene/poly(styrene-co-maleic anhydride) (PS/PSMA) nanofibers as cross-linked enzyme aggregates (CLEA). The lysozyme capacity of PS/PSMA nanofibers under optimal condition was 57.6 mg/g of nanofibers. Various parameters were used to evaluate the stability of the immobilized CLEA-lysozyme. Compared to free ...

Myeloperoxidase (MPO) is a prime candidate for promoting oxidative stress during inflammation. This abundant enzyme of neutrophils uses hydrogen peroxide to oxidize chloride to highly reactive and toxic chlorine bleach. We have identified 2-thioxanthines as potent mechaniism-based inhibitors of MPO. Mass spectrometry and X-ray crystal structures revealed that these inhibitors ...

L: -Ribose is a non-natural and expensive sugar that can be used as an important intermediate for the synthesis of L: -nucleoside analogues, which are used as antiviral drugs. In contrast to chemical production, biotechnological methods can produce L: -ribose from biomass under environmentally friendly conditions. In this mini-review, various ...

The overall objective of this study is to evaluate the morphological [scanning electron microscopy (SEM)], physicochemical [differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), chemical composition analysis, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR)], and biochemical properties of Candida rugosa lipase (CRL) immobilized on a natural biopolymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) in ...

Activation of the Keap1/Nrf2 pathway and consequent induction of phase 2 antioxidant enzymes is known to afford neuroprotection. Here, we present a series of novel electrophilic compounds that protect neurons via this pathway. Natural products, such as carnosic acid (CA), are present in high amounts in the herbs rosemary and ...

γ-Tocopherol methyltransferase (γ-TMT) (EC 2.1.1.95) is a very important enzyme in tocopherol biosynthesis in all photosynthetic organisms. In this paper we present the functional characterization and expression analysis of γ-TMT from the unicellular green alga Chlamydomonas reinhardtii. Recombinant TMT1 enzyme was purified and characterized. The size of TMT1 subunit was ...

α-Galactosidase from tomato has been immobilized on Sepabead EC-EA and Sepabead EC-HA, which were activated with ethylendiamino and hexamethylenediamino groups, respectively. Two strategy was used for the covalent immobilization of α-galactosidase on the aminated Sepabeads: covalent immobilization of enzyme on glutaraldehyde activated support and cross-linking of the adsorbed enzymes on ...

A new efficient immobilization method that enables oriented immobilization of biologically active proteins was developed based on concepts of active site masking and kinetic control. Taq DNA polymerase was immobilized covalently on mixed self-assembled monolayers (SAMs) of ω-carboxylated thiol and ω-hydroxylated thiol through amide bonds between the protein and the ...

An experimental design was carried out to evaluate the effect of the concentrations of sodium alginate, glutaraldehyde and activated coal on the immobilization of inulinase from Kluyveromyces marxianus NRRL Y-7571. The experimental condition of 20 g/L of sodium alginate, 50 mL/L of glutaraldehyde and 30 g/L of activated coal led to the highest ...

α-Amylase from Aspergillus oryzae was covalently immobilized onto polystyrene pellets with pentaethylenehexamine (PS-PEHA-Ald) and pentaethylene glycol (PS-PG-Ald) carrying a terminal aldehyde group. Optimum immobilization occured at pH 8.0 and 25°C, and at pH 7.0 and 35°C for PS-PEHA-Ald and PS-PG-Ald, respectively. PS-PEHA-Ald immobilized enzyme retained approximately 75% of the initial ...

ABSTRACT: BACKGROUND: Adenosine 5-triphosphate (ATP) and its breakdown products ADP and adenosine can act as extracellular messengers in a range of biological processes. Extracellular adenine nucleotides are metabolized by a number of enzymes including NTPDases and 5'-nucleotidase, which are considered to be the major regulators of purinergic signaling in the ...

α-L: -Rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg of ...

An oxidative enzyme, horseradish peroxidase (HRP), was immobilized on phosphorus and/or calcium modified MCM-41 mesoporous silicas with suitable pore diameter. The structural analyses by means of XRD and nitrogen adsorption confirmed that the P and/or Ca modified MCM-41 materials retained their structural quality even after the modification or the enzyme ...

The ammonia plasma process was used for generating reactive groups, particularly primary amine functions on the surface of polyethylene (PE) films, in order to immobilize the enzyme trypsin. The attachment of the enzyme was achieved by directly applying a aqueous solution of trypsin to the plasma activated surface, or by ...

ABSTRACT: In this study, zinc oxide (ZnO) nanocrystals with different morphologies were synthesized and used as substrates for enzyme immobilization. The effects of morphology of ZnO nanocrystals on enzyme immobilization and their catalytic activities were investigated. The ZnO nanocrystals were prepared through a hydrothermal procedure using tetramethylammonium hydroxide as a ...

The use of cell wall degrading enzymes from Trichoderma asperellum immobilized on biodegradable support is an alternative for food packaging. In this study, hydrolytic enzymes produced by T. asperellum were tested as a fungal growth inhibitor, in free form or immobilized on a biodegradable film composed of cassava starch and ...

Lipase from Geobacillus thermocatenulatus (BTL2) was immobilized in two different matrixes. In one derivative, the enzyme was immobilized on agarose activated with cyanogen bromide (CNBr-BTL2) via its most reactive superficial amino group, whereas the other derivative was covalently immobilized on glyoxyl agarose supports (Gx-BTL2). The latter immobilization protocol leads to ...

Lipase B from Candida antarctica (CAL-B) has been site-directedly modified by the introduction of a trans,trans-hexadiene moiety onto lipase molecules, identified by MALDI-TOF. This modification on CAL-B permitted its immobilization on Q-Sepharose supports in excellent yields (>95%) when native lipase was not immobilized at pH 7 and 25 °C. After ...

β-Galactosidase is an important enzyme catalyzing not only the hydrolysis of lactose to the monosaccharides glucose and galactose but also the transgalactosylation reaction to produce galacto-oligosaccharides (GOS). In this study, β-galactosidase was immobilized by adsorption on a mixed-matrix membrane containing zirconium dioxide. The maximum β-galactosidase adsorbed on these membranes was ...

Lysosomal enzymes isolated from egg white were directly immobilized on titanium (IV) oxide (TiO(2)) particles using shaking methods (150rpm, room temperature, 10min), and the immobilization efficiency, activity, and stability of lysosomal enzymes immobilized on TiO(2) were evaluated. Of the various mass ratios (w/w) of lysosomal enzymes to TiO(2) tested, we ...

Cofactor-dependent multi-step enzymatic reactions generally require dynamic interactions among cofactor, enzyme and substrate molecules. Maintaining such molecular interactions can be quite challenging especially when the catalysts are tethered to solid state supports for heterogeneous catalysis for either biosynthesis or biosensing. The current work examines the effects of the pattern of ...

Cyanobacterial toxins have adverse effects on both terrestrial and aquatic plants. Agricultural plants may come in contact with cyanobacterial toxins when surface waters are used for its irrigation. In the present study the effects of MC-LR and cyanobacterial crude extract on three variants of bean by irrigating the seedlings with ...