Showing papers on "Enzyme assay published in 2013"

Modifying enzyme activity and selectivity by immobilization.

Abstract: Immobilization of enzymes may produce alterations in their observed activity, specificity or selectivity. Although in many cases an impoverishment of the enzyme properties is observed upon immobilization (caused by the distortion of the enzyme due to the interaction with the support) in some instances such properties may be enhanced by this immobilization. These alterations in enzyme properties are sometimes associated with changes in the enzyme structure. Occasionally, these variations will be positive. For example, they may be related to the stabilization of a hyperactivated form of the enzyme, like in the case of lipases immobilized on hydrophobic supports via interfacial activation. In some other instances, these improvements will be just a consequence of random modifications in the enzyme properties that in some reactions will be positive while in others may be negative. For this reason, the preparation of a library of biocatalysts as broad as possible may be a key turning point to find an immobilized biocatalyst with improved properties when compared to the free enzyme. Immobilized enzymes will be dispersed on the support surface and aggregation will no longer be possible, while the free enzyme may suffer aggregation, which greatly decreases enzyme activity. Moreover, enzyme rigidification may lead to preservation of the enzyme properties under drastic conditions in which the enzyme tends to become distorted thus decreasing its activity. Furthermore, immobilization of enzymes on a support, mainly on a porous support, may in many cases also have a positive impact on the observed enzyme behavior, not really related to structural changes. For example, the promotion of diffusional problems (e.g., pH gradients, substrate or product gradients), partition (towards or away from the enzyme environment, for substrate or products), or the blocking of some areas (e.g., reducing inhibitions) may greatly improve enzyme performance. Thus, in this tutorial review, we will try to list and explain some of the main reasons that may produce an improvement in enzyme activity, specificity or selectivity, either real or apparent, due to immobilization.

High-throughput fluorometric measurement of potential soil extracellular enzyme activities.

Abstract: Microbes in soils and other environments produce extracellular enzymes to depolymerize and hydrolyze organic macromolecules so that they can be assimilated for energy and nutrients. Measuring soil microbial enzyme activity is crucial in understanding soil ecosystem functional dynamics. The general concept of the fluorescence enzyme assay is that synthetic C-, N-, or P-rich substrates bound with a fluorescent dye are added to soil samples. When intact, the labeled substrates do not fluoresce. Enzyme activity is measured as the increase in fluorescence as the fluorescent dyes are cleaved from their substrates, which allows them to fluoresce. Enzyme measurements can be expressed in units of molarity or activity. To perform this assay, soil slurries are prepared by combining soil with a pH buffer. The pH buffer (typically a 50 mM sodium acetate or 50 mM Tris buffer), is chosen for the buffer's particular acid dissociation constant (pKa) to best match the soil sample pH. The soil slurries are inoculated with a nonlimiting amount of fluorescently labeled (i.e. C-, N-, or P-rich) substrate. Using soil slurries in the assay serves to minimize limitations on enzyme and substrate diffusion. Therefore, this assay controls for differences in substrate limitation, diffusion rates, and soil pH conditions; thus detecting potential enzyme activity rates as a function of the difference in enzyme concentrations (per sample). Fluorescence enzyme assays are typically more sensitive than spectrophotometric (i.e. colorimetric) assays, but can suffer from interference caused by impurities and the instability of many fluorescent compounds when exposed to light; so caution is required when handling fluorescent substrates. Likewise, this method only assesses potential enzyme activities under laboratory conditions when substrates are not limiting. Caution should be used when interpreting the data representing cross-site comparisons with differing temperatures or soil types, as in situ soil type and temperature can influence enzyme kinetics.

The synergistic action of accessory enzymes enhances the hydrolytic potential of a “cellulase mixture” but is highly substrate specific

Abstract: Currently, the amount of protein/enzyme required to achieve effective cellulose hydrolysis is still too high. One way to reduce the amount of protein/enzyme required is to formulate a more efficient enzyme cocktail by adding so-called accessory enzymes such as xylanase, lytic polysaccharide monooxygenase (AA9, formerly known as GH61), etc., to the cellulase mixture. Previous work has shown the strong synergism that can occur between cellulase and xylanase mixtures during the hydrolysis of steam pretreated corn stover, requiring lower protein loading to achieve effective hydrolysis. However, relatively high loadings of xylanases were required. When family 10 and 11 endo-xylanases and family 5 xyloglucanase were supplemented to a commercial cellulase mixture varying degrees of improved hydrolysis over a range of pretreated, lignocellulosic substrates were observed. The potential synergistic interactions between cellulase monocomponents and hemicellulases from family 10 and 11 endo-xylanases (GH10 EX and GH11 EX) and family 5 xyloglucanase (GH5 XG), during hydrolysis of various steam pretreated lignocellulosic substrates, were assessed. It was apparent that the hydrolytic activity of cellulase monocomponents was enhanced by the addition of accessory enzymes although the “boosting” effect was highly substrate specific. The GH10 EX and GH5 XG both exhibited broad substrate specificity and showed strong synergistic interaction with the cellulases when added individually. The GH10 EX was more effective on steam pretreated agriculture residues and hardwood substrates whereas GH5 XG addition was more effective on softwood substrates. The synergistic interaction between GH10 EX and GH5 XG when added together further enhanced the hydrolytic activity of the cellulase enzymes over a range of pretreated lignocellulosic substrates. GH10 EX addition could also stimulate further cellulose hydrolysis when added to the hydrolysis reactions when the rate of hydrolysis had levelled off. Endo-xylanases and xyloglucanases interacted synergistically with cellulases to improve the hydrolysis of a range of pretreated lignocellulosic substrates. However, the extent of improved hydrolysis was highly substrate dependent. It appears that those accessory enzymes, such as GH10 EX and GH5 XG, with broader substrate specificities promoted the greatest improvements in the hydrolytic performance of the cellulase mixture on all of the pretreated biomass substrates.

Microbial Responses to Multi-Factor Climate Change: Effects on Soil Enzymes.

Abstract: The activities of extracellular enzymes, the proximate agents of decomposition in soils, are known to depend strongly on temperature, but less is known about how they respond to changes in precipitation patterns, and the interaction of these two components of climate change. Both enzyme production and turnover can be affected by changes in temperature and soil moisture, thus it is difficult to predict how enzyme pool size may respond to altered climate. Soils from the Boston-Area Climate Experiment (BACE), which is located in an old field (on abandoned farmland), were used to examine how climate variables affect enzyme activities and microbial biomass carbon (MBC) in different seasons and in soils exposed to a combination of three levels of precipitation treatments (ambient, 150% of ambient during growing season, and 50% of ambient year-round) and four levels of warming treatments (unwarmed to ~4°C above ambient) over the course of a year. Warming, precipitation and season had very little effect on potential enzyme activity. Most models assume that enzyme dynamics follow microbial biomass, because enzyme production should be directly controlled by the size and activity of microbial biomass. We observed differences among seasons and treatments in mass-specific potential enzyme activity, suggesting that this assumption is invalid. In June 2009, mass-specific potential enzyme activity, using chloroform fumigation-extraction MBC, increased with temperature, peaking under medium warming and then declining under the highest warming. This finding suggests that either enzyme production increased with temperature or turnover rates decreased. Increased maintenance costs associated with warming may have resulted in increased mass-specific enzyme activities due to increased nutrient demand. Our research suggests that allocation of resources to enzyme production could be affected by climate-induced changes in microbial efficiency and maintenance costs.

Molecular cloning of rice serotonin N-acetyltransferase, the penultimate gene in plant melatonin biosynthesis

Abstract: Because of the absence of an arylalkylamine N-acetyltransferase (AANAT) homolog in the plant genome, the proposal was made that a GCN5-related N-acetyltransferase superfamily gene (GNAT) could be substituted for AANAT. To clone rice serotonin N-acetyltransferase (SNAT), we expressed 31 rice GNAT cDNAs in Escherichia coli and screened SNAT activity by measuring N-acetyltryptamine after application with 1 mm tryptamine. GNAT5 was shown to produce high levels of N-acetyltryptamine in E. coli, suggesting a possible rice SNAT. To confirm SNAT activity, the GNAT5 protein was purified through affinity purification from E. coli culture. The purified recombinant GNAT5 showed high SNAT enzyme activity catalyzing serotonin into N-acetylserotonin. The values for Km and Vmax were 385 μm and 282 pmol/min/mg protein, respectively. An in vitro enzyme assay of purified SNAT showed N-acetylserotonin formation to be proportional to enzyme concentration and time, with peak activity at pH 8.8. High substrate concentrations above 1 mm serotonin inhibited SNAT activity. Finally, the mRNA level of SNAT was higher in shoots than in roots, but it was expressed constitutively, unlike N-acetylserotonin methyltransferase (ASMT), the terminal enzyme in melatonin synthesis. These results suggest that ASMT rather than SNAT is the rate-limiting enzyme of melatonin biosynthesis in plants.

Production and partial characterization of extracellular amylase enzyme from Bacillus amyloliquefaciens P-001

Abstract: Amylases are one of the most important enzymes in present-day biotechnology. The present study was concerned with the production and partial characterization of extracellular amylase from Bacillus amyloliquefaciens P-001. The effect of various fermentation conditions on amylase production through shake-flask culture was investigated. Enzyme production was induced by a variety of starchy substrate but corn flour was found to be a suitable natural source for maximum production. Tryptone and ammonium nitrate (0.2%) as nitrogen sources gave higher yield compared to other nitrogen sources. Maximum enzyme production was obtained after 48 hrs of incubation in a fermentation medium with initial pH 9.0 at 42°C under continuous agitation at 150 rpm. The size of inoculum was also optimized which was found to be 1% (v/v). Enzyme production was 2.43 times higher after optimizing the production conditions as compared to the basal media. Studies on crude amylase revealed that optimum pH, temperature and reaction time of enzyme activity was 6.5, 60°C and 40 minutes respectively. About 73% of the activity retained after heating the crude enzyme solution at 50°C for 30 min. The enzyme was activated by Ca2+ (relative activity 146.25%). It was strongly inhibited by Mn2+, Zn2+ and Cu2+, but less affected by Mg2+ and Fe2+.

Inhibition of α-Amylase and Glucoamylase by Tannins Extracted from Cocoa, Pomegranates, Cranberries, and Grapes

Abstract: Proanthocyanidins and ellagitannins, referred to as “tannins”, exist in many plant sources. These compounds interact with proteins due to their numerous hydroxyl groups, which are suitable for hydrophobic associations. It was hypothesized that tannins could bind to the digestive enzymes α-amylase and glucoamylase, thereby inhibiting starch hydrolysis. Slowed starch digestion can theoretically increase satiety by modulating glucose “spiking” and depletion that occurs after carbohydrate-rich meals. Tannins were isolated from extracts of pomegranate, cranberry, grape, and cocoa and these isolates tested for effectiveness to inhibit the activity of α-amylase and glucoamylase in vitro. The compositions of the isolates were confirmed by NMR and LC/MS analysis, and tannin–protein interactions were investigated using relevant enzyme assays and differential scanning calorimetry (DSC). The results demonstrated inhibition of each enzyme by each tannin, but with variation in magnitude. In general, larger and more com...

Modifying Enzyme Activity and Selectivity by Immobilization

Abstract: Immobilization of enzymes may produce alterations in their observed activity, specificity or selectivity. Although in many cases an impoverishment of the enzyme properties is observed upon immobilization (caused by the distortion of the enzyme due to the interaction with the support) in some instances such properties may be enhanced by this immobilization. These alterations in enzyme properties are sometimes associated with changes in the enzyme structure. Occasionally, these variations will be positive. For example, they may be related to the stabilization of a hyperactivated form of the enzyme, like in the case of lipases immobilized on hydrophobic supports via interfacial activation. In some other instances, these improvements will be just a consequence of random modifications in the enzyme properties that in some reactions will be positive while in others may be negative. For this reason, the preparation of a library of biocatalysts as broad as possible may be a key turning point to find an immobilized biocatalyst with improved properties when compared to the free enzyme. Immobilized enzymes will be dispersed on the support surface and aggregation will no longer be possible, while the free enzyme may suffer aggregation, which greatly decreases enzyme activity. Moreover, enzyme rigidification may lead to preservation of the enzyme properties under drastic conditions in which the enzyme tends to become distorted thus decreasing its activity. Furthermore, immobilization of enzymes on a support, mainly on a porous support, may in many cases also have a positive impact on the observed enzyme behavior, not really related to structural changes. For example, the promotion of diffusional problems (e.g., pH gradients, substrate or product gradients), partition (towards or away from the enzyme environment, for substrate or products), or the blocking of some areas (e.g., reducing inhibitions) may greatly improve enzyme performance. Thus, in this tutorial review, we will try to list and explain some of the main reasons that may produce an improvement in enzyme activity, specificity or selectivity, either real or apparent, due to immobilization.

Soil zymography – A novel in situ method for mapping distribution of enzyme activity in soil

Abstract: Recently, there has been growing interest in the spatial distribution of microbial activity in soil; however, methods for analysis of spatial distribution of microbial activity and for localization of hotspots of enzyme activity in soil are limited. Here were present an in situ zymography technique for localization and quantification of enzyme activities in soil by means of thin gels with embedded substrates. After incubation, the substrate remaining in the gel is colored and quantified using calibration curves and digital image analysis. So far, zymography has mostly been used to localize enzymatic activity in electrophoresis gels and in tissue sections. In this study we developed a zymography technique for analysis of the two-dimensional distribution of enzyme activities in soil. The technique was applied to map and quantify protease and amylase activity in the rhizosphere of lupine (Lupinus polyphyllus) grown in rhizoboxes. Highest activities, of up to 46 ng mm � 2 of the soil surface h � 1 for the protease and of up to 0.90 m gm m � 2 h � 1 for the amylase were found in close association with roots. Since zymography is an in situ method that does not require destruction of soil structure, it likely pictures enzyme activities more realistically than standard enzyme assays. In conclusion, soil in situ zymography offers a promising tool for mapping distributions of enzyme activities in soils in a work- and cost-efficient way.

Organic matter inputs shift soil enzyme activity and allocation patterns in a wet tropical forest

Abstract: Soil extracellular enzymes mediate organic matter turnover and nutrient cycling yet remain little studied in one of Earth’s most rapidly changing, productive biomes: tropical forests. Using a long-term leaf litter and throughfall manipulation, we explored relationships between organic matter (OM) inputs, soil chemical properties and enzyme activities in a lowland tropical forest. We assayed six hydrolytic soil enzymes responsible for liberating carbon (C), nitrogen (N) and phosphorus (P), calculated enzyme activities and ratios in control plots versus treatments, and related these to soil biogeochemical variables. While leaf litter addition and removal tended to increase and decrease enzyme activities per gram soil, respectively, shifts in enzyme allocation patterns implied changes in relative nutrient constraints with altered OM inputs. Enzyme activity ratios in control plots suggested strong belowground P constraints; this was exacerbated when litter inputs were curtailed. Conversely, with double litter inputs, increased enzymatic investment in N acquisition indicated elevated N demand. Across all treatments, total soil C correlated more strongly with enzyme activities than soluble C fluxes, and enzyme ratios were sensitive to resource stoichiometry (soil C:N) and N availability (net N mineralization). Despite high annual precipitation in this site (MAP ~5 m), soil moisture positively correlated with five of six enzymes. Our results suggest resource availability regulates tropical soil enzyme activities, soil moisture plays an additional role even in very wet forests, and relative investment in C, N and P degrading enzymes in tropical soils will often be distinct from higher latitude ecosystems yet is sensitive to OM inputs.

Photoswitching of Enzyme Activity by Laser-Induced pH-Jump

Abstract: Controlled initiation of biochemical events and in particular of protein activity is a powerful tool in biochemical research. Specifically, optical trigger signals are an attractive approach for remote control of enzyme activity. We present a method for generating optical control of enzyme activity applicable to a widespread range of enzymes. The approach is based on short laser pulses as optical “switches” introducing an instantaneous change of the pH-value for activation of protein function. The pH-jump is induced by proton release from 2-nitrobenzaldehyde. Reaction conditions were chosen to yield a pH-jump of almost 3 units on switching from inactive to active conditions for the enzyme. In this experimental setup, irradiation can be realized without any loss of enzyme activity. Following this change in pH-value, a controlled activation of hydrolytic activity of acid phosphatase is successfully demonstrated. This application provides a general method for photocontrol of enzymatic function for proteins h...

Purification, characterization and kinetic properties of extracellular L-asparaginase produced by Cladosporium sp.

Abstract: l-asparaginase from Cladosporium sp. grown on wheat bran by SSF was purified. Enzyme appeared to be a trimer with homodimer of 37 kDa and another 47 kDa amounting to total mass of 121 kDa as estimated by SDS-PAGE and 120 kDa on gel filtration column. The optimum temperature and pH of the enzyme were 30 °C and 6.3, respectively with Vmax of 4.44 μmol/mL/min and Km of 0.1 M. Substrate specificity studies indicated that, l-asparaginase has greater affinity towards l-asparagine with substrate hydrolysis efficiency (Vmax/Km ratio) eightfold higher than that of l-glutamine. l-asparaginase activity in presence of thiols studied showed decrease in Vmax and increase in Km, indicating nonessential mode of inactivation. Among the thiols tested, β-mercaptomethanol, exerted inhibitory effect, suggesting a critical role of disulphide linkages in maintaining a suitable conformation of the enzyme. Metal ions such as Ca2+, Co2+, Cu2+, Mg2+, Na+, K+ and Zn2+ significantly affected enzyme activity whereas presence of Fe3+, Pb2+ and KI stimulated the activity. Detergents studied also enhanced l-asparaginase activity. In-vitro half-life of purified l-asparaginase in mammalian blood serum was 93.69 h. The enzyme inhibited acrylamide formation in potato chips by 96 % making it a potential candidate for food industry to reduce acrylamide content in starchy fried food commodities.

Structural basis for the functional roles of critical residues in human cytochrome p450 aromatase.

Abstract: Cytochrome P450 aromatase (CYP19A1) is the only enzyme known to catalyze the biosynthesis of estrogens from androgens. The crystal structure of human placental aromatase (pArom) has paved the way toward understanding the structure-function relationships of this remarkable enzyme. Using an amino terminus-truncated recombinant human aromatase (rArom) construct, we investigate the roles of key amino acids in the active site, at the intermolecular interface, inside the access channel, and at the lipid-protein boundary for their roles in enzyme function and higher-order organization. Replacing the active site residue D309 with an N yields an inactive enzyme, consistent with its proposed involvement in aromatization. Mutation of R192 at the lipid interface, pivotal to the proton relay network in the access channel, results in the loss of enzyme activity. In addition to the distal catalytic residues, we show that mutation of K440 and Y361 of the heme-proximal region critically interferes with substrate binding, enzyme activity, and heme stability. The D-E loop deletion mutant Del7 that disrupts the intermolecular interaction significantly reduces enzyme activity. However, the less drastic Del4 and point mutants E181A and E181K do not. Furthermore, native gel electrophoresis, size-exclusion chromatography, and analytical ultracentrifugation are used to show that mutations in the intermolecular interface alter the quaternary organization of the enzyme in solution. As a validation for interpretation of the mutational results in the context of the innate molecule, we determine the crystal structure of rArom to show that the active site, tertiary, and quaternary structures are identical to those of pArom.

Light-triggered biocatalysis using thermophilic enzyme-gold nanoparticle complexes.

Abstract: The use of plasmonic nanoparticle complexes for biomedical applications such as imaging, gene therapy, and cancer treatment is a rapidly emerging field expected to significantly improve conventional medical practices. In contrast, the use of these types of nanoparticles to noninvasively trigger biochemical pathways has been largely unexplored. Here we report the light-induced activation of the thermophilic enzyme Aeropyrum pernix glucokinase, a key enzyme for the decomposition of glucose via the glycolysis pathway, increasing its rate of reaction 60% with light by conjugating the enzyme onto Au nanorods. The observed increase in enzyme activity corresponded to a local temperature increase within a calcium alginate encapsulate of ~20 °C when compared to the bulk medium maintained at standard, nonthermophilic temperatures. The encapsulated nanocomplexes were reusable and stable for several days, making them potentially useful in industrial applications. This approach could significantly improve how biochemical pathways are controlled for in vitro and, quite possibly, in vivo use.

Microbial Enzymes and Their Applications in Industries and Medicine 2016.

Abstract: Enzymes are considered as a potential biocatalyst for a large number of reactions. Particularly, the microbial enzymes have widespread uses in industries and medicine. The microbial enzymes are also more active and stable than plant and animal enzymes. In addition, the microorganisms represent an alternative source of enzymes because they can be cultured in large quantities in a short time by fermentation and owing to their biochemical diversity and susceptibility to gene manipulation. Industries are looking for new microbial strains in order to produce different enzymes to fulfil the current enzyme requirements. This special issue covers ten articles including three review articles, mainly highlighting the importance and applications of biotechnologically and industrially valuable microbial enzymes. M. Dinarvand et al. in their paper optimized the conditions for overproduction of intraextracellular inulinase and invertase from the fungus Aspergillus niger ATCC 20611. Optimization is one of the most important criteria in developing any new microbial process. Response surface analysis is one of the vital tools to determine the optimal process conditions. This kind of design of a limited set of variables is advantageous compared to the conventional method. The response surface methodology was used for this optimization and achieved the increment until 16 times. This study would be highly useful for the potential application in fermentation industries. In this review, N. Gurung et al. have made an attempt to highlight the importance of different enzymes with a special focus on amylase and lipase. Enzymes generally increase the reaction rates by several million times than normal chemical reactions. Lipases play an important role in the food, detergent, chemical, and pharmaceutical industries. In the past, microbial lipases gained significant attention in the industries due to their substrate specificity and stability under varied conditions. Amylase is an enzyme that catalyses the breakdown of starch into sugars, abundant in the process of animal and human digestion. The major advantage of microbial amylases is being economical and easy to manipulate. Currently, much attention is paid to rapid development of microbial enzyme technology, and these enzymes are relatively more stable than the enzymes derived from plants and animals. P. Mukherjee and P. Roy in their paper have purified and characterized the enzyme hydrocarbon dioxygenase from Stenotrophomonas maltophilia PM102, which has a broad substrate specificity. They found that the presence of copper induces the enzyme activity to be 10.3-fold higher, and NADH induces the increment to be 14.96-fold. Proposed copper enhanced monooxygenase activity and Fourier transform-infrared (FT-IR) characterization of biotransformation products from trichloroethylene satisfy the production of industrially and medically important chemicals and make bioremediation more attractive by improving the development of this technology. C. Huynen et al. in their review paper discuss the importance of protein scaffold to develop hybrid enzymes. The paper discusses the use of class A betalactamase as versatile scaffolds to design hybrid enzymes mentioned as betalactamase hybrid proteins (BHPs), in which an external polypeptide, peptide, protein, or their fragment is inserted at various suitable positions. The paper highlights further how BHPs can be specifically designed to develop as bifunctional proteins to produce and characterize the proteins otherwise difficult to express, to determine the epitope of specific antibodies, to generate antibodies against nonimmunogenic epitopes, and to understand the structure/function relationship of proteins. The hybrid proteins can be applied to produce difficult-to-express peptides/proteins/protein fragments, to map epitopes, to display antigens, and to study protein structure/function relationships. Among other applications, BHPs could be an important player in biosensors and in affinity chromatography, drug screening, and drug targeting. P. Manivasagan et al. in their paper focus on purification and characterization of the protease from Streptomyces sp. MAB18. The authors have optimized the conditions for overproduction of protease using response surface methodology. They have also determined the molecular mass of purified enzyme and great activity and stability of enzyme in different pH and temperatures. Furthermore, the authors confirmed that the protease has an antioxidant ability. In industries, the poultry waste derived protease will be useful as a protein or as an antioxidant. The paper titled “β-Glucosidases from the fungus Trichoderma: an effeicient cellulose machinery in biotechnological applications” is a detailed review on β-glucosidases which are members of the cellulose enzyme complex described by P. Tiwari et al. The authors especially focus on β-glucosidases from the fungus Trichoderma, mostly used for the saccharification of cellulosic biomass for biofuel production. They describe the enzyme family, their classification, structural parameters, properties, and studies at the genomics and proteomics levels. In addition, by bypassing the low enzyme production with hypersecretory strains, they give an insight on using these strains for renewable energy sources like bioethanol production. They imply the importance of fungal β-glucosidases which might be successful for biofuel production in order to meet the need in energy crisis. A. Khoramnia et al. in their paper discuss yeast enzyme application for medium chain fatty acids (MCFAs) modification for industrial purpose and antibacterial applications. The paper focuses on the conceptualization, design, and assay of the enzyme produced from a Malaysian strain of Geotrichum candidum. With the modification on fatty acid processing using a naturally derived enzyme, a free lauric acid rich MCFAs can be obtained which can become a source of antibacterial use for both Gram-positive (Staphylococcus aureus) and Gram-negative (E. coli) bacteria which are difficult microbes due to some of their strains becoming drug resistant. They also describe that the higher lipolysis by the strain specific enzyme is associated with the increased moisture content in the reaction environment on coconut oil hydrolysis. M. A. Hassan et al. in their paper discuss isolation of Bacillus amyloliquefaciencs and B. subtilis from soil and production and characterization of keratinolytic protease. These bacteria were able to degrade the wool completely within 5 days and also produced the highest enzyme activity. The characterization studies confirmed that the enzyme is stable in a broad range of pH and temperatures. Furthermore, they confirmed that the keratinolytic proteases from isolated bacteria are stable in various organic solvents. In this review article, S. C. B. Gopinath et al. put different strategies to characterize fungal lipases for their role in industry and medicine. The advantage of fungal lipases is bestowed with their extracellular nature of production thus reducing the complexities and high operation cost comparing to other bacterial enzymes. The authors provide several illustrations to show how lipolysis can be utilized and put strategies for the characterization of fungal lipases that are capable of degrading fatty substances from different sources, with an effort to highlight further applications. This review would contribute to the isolation and characterization of lipase from various fungal sources and application of lipase for medical and dairy industry and degradation of fatty substance from oil spillages. A. Knob et al. in their paper focus on xylanses and discuss the purification and characterization of a xylanase produced by Penicillium glabrum using brewer's spent grain as a substrate in their paper. This study is the first report as the characterization of xylanase was carried out by using such an agroindustrial waste. Furthermore, the researchers also determined the molecular mass of the purified xylanase, the enzyme activity and stability on various pH and temperature ranges, the optimal enzyme production conditions, and the effect of some metal ions and inhibitors on xylanase activity. The authors concluded that the use of substrate brewer's spent grain for xylanase production not only decreased the amount of this waste but also reduced the xylanase production cost as desired in biotechnological processes. Periasamy Anbu Subash C. B. Gopinath Arzu Coleri Cihan Bidur Prasad Chaulagain

Cloning, expression and characterization of an ethanol tolerant GH3 β-glucosidase from Myceliophthora thermophila.

Abstract: The β-glucosidase gene bgl3a from Myceliophthora thermophila, member of the fungal glycosyl hydrolase (GH) family 3, was cloned and expressed in Pichia pastoris. The mature β-glucosidase gene, which results after the excision of one intron and the secreting signal peptide, was placed under the control of the strong alcohol oxidase promoter (AOX1) in the plasmid pPICZαC. The recombinant enzyme (90 kDa) was purified and characterized in order to evaluate its biotechnological potential. Recombinant P. pastoris efficiently secreted β-glucosidase into the medium and produced high level of enzymatic activity (41 U/ml) after 192 h of growth, under methanol induction. MtBgl3a was able to hydrolyze low molecular weight substrates and polysaccharides containing β-glucosidic residues. The Km was found to be 0.39 mM on p-β-NPG and 2.64 mM on cellobiose. Optimal pH and temperature for the p-β-NPG hydrolysis were 5.0 and 70 °C. The β-glucosidase exhibits a half life of 143 min at 60 °C. Kinetic parameters of inhibition were determined for D-glucose, D-xylose and D-gluconic acid, indicating tolerance of the enzyme for these sugars and oxidized products. The recombinant enzyme was stimulated by short chain alcohols and has been shown to efficiently synthesize methyl-D-glucoside in the presence of methanol due to its transglycosylation activity. The stability of MtBgl3a in ethanol was prominent, and it retained most of its original activity after we exposed it to 50% ethanol for 6 h. The high catalytic performance, good thermal stability and tolerance to elevated concentrations of ethanol, D-xylose and D-glucose qualify this enzyme for use in the hydrolysis of lignocellulosic biomass for biofuel production, as part of an efficient complete multi-enzyme cocktail.

Novel glyoxalases from Arabidopsis thaliana

Abstract: We examined six Arabidopsis thaliana genes from the DJ-1/PfpI superfamily for similarity to the recently characterized bacterial and animal glyoxalases Based on their sequence similarities, the six genes were classified into two sub-groups consisting of homologs of the human DJ-1 gene and the PH1704 gene of Pyrococcus horikoshii Unlike the homologs from other species, all the A thaliana genes have two tandem domains, which may have been created by gene duplication The six AtDJ-1 proteins (a-f) were expressed in Escherichia coli for enzymatic assays with glyoxals The DJ-1d protein, which belongs to the PH1704 sub-group, exhibits the highest activity against methylglyoxal and glyoxal, and K(m) values of 010 and 027 mm were measured for these two substrates, respectively, while the corresponding k(cat) values were 1700 and 2200 min(-1), respectively The DJ-1a and DJ-1b glyoxalases exhibited higher specificity towards glyoxal The other three proteins have either no or extremely low activity for glyoxals For the DJ-1d enzyme, the residues, Cys120/313 and Glu19/212 at the active site and His121/314 and Glu94/287 at the oligomeric interface were mutated to alanines As in other enzymes characterized to date, mutation of either the Cys or the Glu residues of the active site completely abolished enzyme activity, whereas mutation of the interface residues produced a variable decrease in activity DJ-1d differs from its animal and bacterial homologs with respect to the configuration of its catalytic residues and the oligomeric property of the enzyme When the wild-type DJ-1d enzyme was expressed in E coli, the bacteria became resistant to glyoxals

Production, Purification, and Characterization of Thermostable α-Amylase Produced by Bacillus licheniformis Isolate AI20

Abstract: An optimization strategy, based on statistical experimental design, is employed to enhance the production of thermostable α-amylase by a thermotolerant B. licheniformis AI20 isolate. Using one variant at time (OVAT) method, starch, yeast extract, and CaCl2 were observed to influence the enzyme production significantly. Thereafter, the response surface methodology (RSM) was adopted to acquire the best process conditions among the selected variables, where a three-level Box-Behnken design was employed to create a polynomial quadratic model correlating the relationship between the three variables and α-amylase activity. The optimal combination of the major constituents of media for α-amylase production was 1.0% starch, 0.75% yeast extract, and 0.02% CaCl2. The predicted optimum α-amylase activity was 384 U/mL/min, which is two folds more than the basal medium conditions. The produced α-amylase was purified through various chromatographic techniques. The estimated enzyme molecular mass was 55 kDa and the α-amylase had an optimal temperature and pH of 60–80°C and 6–7.5, respectively. Values of and for the purified enzyme were 454 mU/mg and 0.709 mg/mL. The α-amylase enzyme showed great stability against different solvents. Additionally, the enzyme activity was slightly inhibited by detergents, sodium dodecyl sulphate (SDS), or chelating agents such as EDTA and EGTA. On the other hand, great enzyme stability against different divalent metal ions was observed at 0.1 mM concentration, but 10 mM of Cu2

Immobilization of α-amylase on gum acacia stabilized magnetite nanoparticles, an easily recoverable and reusable support

Abstract: In this work, α-amylase is immobilized, using glutaraldehyde, onto magnetite nanoparticles prepared using gum acacia as the steric stabilizer (GA-MN), for the first time. The immobilization of amylase to GA-MN is very fast and the synthesis of GA-MN is very simple. The use of GA enables higher immobilization of α-amylase (60%), in contrast to the unmodified magnetite nanoparticles (∼20%). The optimum pH and temperature for maximum enzyme activity for the immobilized amylase are identified to be 7.0 and 40 °C, respectively, for the hydrolysis of starch. The kinetic studies confirm the Michaelis–Menten behavior and suggests overall enhancement in the performance of the immobilized enzyme with reference to the free enzyme. Similarly the thermal stability of the enzyme is found to increase after the immobilization. The GA-MN bound amylase has also been demonstrated to be capable of being reused for at least six cycles while retaining ∼70% of the initial activity. By using a magnetically active support, quick separation of amylase from reaction mixture is enabled. The catalytic rate of amylase is actually found to enhance by twofold after the immobilization, which is extremely advantageous in industry. At higher temperature, the immobilized enzyme exhibits higher enzyme activity than that of the free enzyme.