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Maximum Activity (maximum + activity)
Selected AbstractsTowards Higher Laccase Activities Produced by Aquatic Ascomycetous Fungi Through Combination of Elicitors and an Alternative SubstrateENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2008C. Junghanns Abstract Laccases are versatile biocatalysts with various potential biotechnological applications, e.g. the treatment of industrial waste waters, the detoxification of environmental pollutants, or the functionalization of renewable polymeric materials. Central composition experimental design and response surface methodology was applied to optimize the production of laccase by the aquatic ascomycetous fungi, Phoma sp. UHH 5-1-03 and Coniothyrium sp.,Kl-S5, in shake flasks. A complex plant-based medium (tomato juice) and two elicitors (Remazol Brilliant Blue R [RBBR] and CuSO4) were tested in combination at three concentrations. The highest laccase activity of 6322,±,403,U/L was achieved on day,9 for Phoma sp. Coniothyrium sp. exerted a maximum laccase activity of 3035,±,111 U/L on day,4. Optimal conditions were 30,% tomato juice and 450,mg/L RBBR for both strains. A concentration of 250,,M CuSO4 led to highest laccase activities in cultures of Coniothyrium sp., and 50,,M CuSO4 was most effective for Phoma sp. A remarkable synergistic effect of tomato juice and RBBR on laccase production was observed for both strains. The upscaling potential of the optimal induction conditions was demonstrated in a lab-scale fermenter which resulted in maximum activities of 11030,±,177,U/L on day,6 for Phoma sp. and 11530,±,161,U/L on day,9 for Coniothyrium sp. This study therefore presents a promising alternative for laccase production in ascomycetes based on a cheap complex substrate in combination with two elicitors. [source] Synthesis and screening of substituted 1,4-naphthoquinones (NPQs) as antifilarial agentsDRUG DEVELOPMENT RESEARCH, Issue 3 2010Nisha Mathew Abstract Eleven amino-substituted 1,4-naphthoquinones were synthesized via the reaction of 1,4-naphthoquinone with different primary and secondary mono- and diamines in the presence of dichloromethane ethanol (1:2) solvent at room temperature. All compounds were purified by flash column chromatography, characterized by TLC, HPLC, 13C-NMR, 1H-NMR, and FT-IR spectral analysis and were evaluated in vitro for antifilarial activity using adult bovine filarial worm Setaria digitata by assessing worm motility and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction. Seven of the 11 compounds had macrofilaricidal activity with compounds 9 (2-[(1,3-dimethylbutyl) amino] naphthalene-1,4-dione) and 11 (2-(4-methylpiperazin-1-yl) naphthalene-1,4-dione) having maximum activity (ED50 values of 0.91 and 1.2,µM, respectively, at 48,h). The effect of different substitutions on antifilarial activity is discussed. Drug Dev Res 2009. © 2009 Wiley-Liss, Inc. [source] Fibre-type composition of rabbit jaw muscles is related to their daily activityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005T. van Wessel Abstract Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20,30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day. [source] Purification, characterization and amino-acid sequence analysis of a thermostable, low molecular mass endo-,-1,4-glucanase from blue mussel, Mytilus edulisFEBS JOURNAL, Issue 16 2000Bingze Xu A cellulase (endo-,-1,4- d -glucanase, EC 3.2.1.4) from blue mussel (Mytilus edulis) was purified to homogeneity using a combination of acid precipitation, heat precipitation, immobilized metal ion affinity chromatography, size-exclusion chromatography and ion-exchange chromatography. Purity was analyzed by SDS/PAGE, IEF and RP-HPLC. The cellulase (endoglucanase) was characterized with regard to enzymatic properties, isoelectric point, molecular mass and amino-acid sequence. It is a single polypeptide chain of 181 amino acids cross-linked with six disulfide bridges. Its molecular mass, as measured by MALDI-MS, is 19 702 Da; a value of 19 710.57 Da was calculated from amino-acid composition. The isoelectric point of the enzyme was estimated by isoelectric focusing in a polyacrylamide gel to a value of 7.6. According to amino-acid composition, the theoretical pI is 7.011. The effect of temperature on the endoglucanase activity, with carboxymethyl cellulose and amorphous cellulose as substrates, respectively, was studied at pH 5.5 and displayed an unusually broad optimum activity temperature range between 30 and 50 °C. Another unusual feature is that the enzyme retains 55,60% of its maximum activity at 0 °C. The enzyme readily degrades amorphous cellulose and carboxymethyl cellulose but displays no hydrolytic activity towards crystalline cellulose (Avicel) and shows no cross-specificity for xylan; there is no binding to Avicel. The enzyme can withstand 10 min at 100 °C without irreversible loss of enzymatic activity. Amino-acid sequence-based classification has revealed that the enzyme belongs to the glycoside hydrolase family 45, subfamily 2 (B. Henrissat, Centre de Recherches sur les Macromolecules Végétales, CNRS, Joseph Fourier Université, Grenoble, France, personal communication). [source] Characterization and heterologous expression of a novel lysophospholipase gene from Antrodia cinnamomeaJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2010K.-H. Hsu Abstract Aims:, A novel lysophospholipase (LysoPL) from the basidiomycetous fungi Antrodia cinnamomea named ACLysoPL was cloned, heteroexpressed in Escherichia coli and characterized. Methods and Results:, The gene encoding ACLysoPL was obtained from expressed sequence tags from A. cinnamomea. The full length of this gene has a 945 -bp open reading frame encoding 314 amino acids with a molecular weight of 35·5 kDa. ACLysoPL contains a lipase consensus sequence (GXSXG) motif and a Ser,His,Asp catalytic triad. A putative peroxisomal targeting signal type 1 was found in the C-terminal. Heterologous expression of ACLysoPL in E. coli showed that the enzyme preferentially hydrolyses long-chain acyl esterases at pH 7 and 30°C. ACLysoPL is a psychrophilic enzyme about 40% of whose maximum activity remained at 4°C. The LysoPL activities with lysophospholipids as substrate were analysed by gas chromatography/mass spectrometry. Conclusion:, We have identified and characterized a gene named ACLysoPL encoding a protein performing LysoPL and esterase activities. Significance and Impact of the Study:, This is the first LysoPL of A. cinnamomea identified and characterized at the molecular level. [source] Sucrose phosphorylase of the rumen bacterium Pseudobutyrivibrio ruminis strain AJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009A. Kasperowicz Abstract Aims:, To verify the taxonomic affiliation of bacterium Butyrivibrio fibrisolvens strain A from our collection and to characterize its enzyme(s) responsible for digestion of sucrose. Methods and Results:, Comparison of the 16S rRNA gene of the bacterium with GenBank showed over 99% sequence identity to the species Pseudobutyrivibrio ruminis. Molecular filtration, native electrophoresis on polyacrylamide gel, zymography and thin layer chromatography were used to identify and characterize the relevant enzyme. An intracellular sucrose phosphorylase with an approximate molecular mass of 52 kDa exhibiting maximum activity at pH 6·0 and temperature 45°C was identified. The enzyme was of inducible character and catalysed the reversible conversion of sucrose to fructose and glucose-1-P. The reaction required inorganic phosphate. The Km for glucose-1-P formation and fructose release were 3·88 × 10,3 and 5·56 × 10,3 mol l,1 sucrose, respectively , while the Vmax of the reactions were ,0·579 and 0·9 ,mol mg protein,1 min,1. The enzyme also released free glucose from glucose phosphate. Conclusion:,Pseudobutyrivibrio ruminis strain A utilized sucrose by phosphorolytic cleavage. Significance and Impact of the Study:, Bacterium P. ruminis strain A probably participates in the transfer of energy from dietetary sucrose to the host animal. [source] Effects of butyric acid stress on anaerobic sludge for hydrogen production from kitchen wastesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Mingxing Zhao Abstract BACKGROUND: Anaerobic digestion is an alternative technology to achieve the dual benefits of hydrogen production and waste stabilization from kitchen wastes. In this work, the butyric acid stress on anaerobic sludge was investigated in order to improve the tolerance of sludge against organic acids, and to enhance hydrogen accumulation. RESULTS: The tolerance of butyric acid in anaerobic sludge increased with the stress concentration, however, it decreased at concentrations greater than of 4.0 g L,1. The maximum hydrogen yield reached 63.72 mL g,1 VS at 4.0 g L,1 stress, representing an increase of 114% compared with the control group. The concentration of volatile solids (VS) of the sludge and SCOD increased steadily with time up to 20 h. At 4.0 g L,1 butyric acid stress, the maximum activity of ,-glucosidase, BAA-hydrolysing protease and dehydrogenase enzyme were 14912.1 µmol PNP g,1 TS h,1, 134.14 µmol NH4 -N g,1 TS h,1 and 7316.42 µg TF g,1 TS h,1, which were 2.78, 1.90 and 2.01 times that of the control, respectively. CONCLUSIONS: The feasibility of butyric acid stress on anaerobic sludge to increase hydrogen production from kitchen wastes was demonstrated. Remarkably, 4.0 g L,1 butyric acid stress was found to be favorable for improving the tolerance of butyric acid in sludge as well as hydrogen yield in the experiment. Copyright © 2010 Society of Chemical Industry [source] Isolation and Characteristics of Bacillus subtilis CN2 and its Collagenase ProductionJOURNAL OF FOOD SCIENCE, Issue 3 2002L. H. Tran ABSTRACT: : An isolated bacterium strain named CN2 found in Vietnamese fish sauce has been identified as Bacillus subtilis. In an enzyme-producing medium with 0% and 8% NaCl concentration, the CN2 strain produced the maximum collagenase activity, 3.07 U/ml and 2.60 U/ml. The strain also produced gelatinase, but the maximum activity was only 1.03 U/ml at 8 h of incubation time and prolonged more than 22 h. Bacillus subtilis CN2, grown slowly in a medium containing 12% NaCl, showed a decreased rate of collagenase activity with a maximum activity of 1.60 U/ml at 18 h of incubation time. The culture supernatant of CN2 strain digested a purified native collagen from rat tail tendon as well as ,s-casein at Met123 -Lys124 position. Therefore The culture supernatant of CN2 can be used to produce healthy foods. [source] Electrostatic-induced interfacial assembly of enzymes with nanosheets: Controlled orientation and optimized activityAICHE JOURNAL, Issue 10 2010Zhe An Abstract In this work, an electrostatic-induced interfacial assembly of porcine pancreatic lipase (PPL) with the nanosheets of layered double hydroxide (LDHNSs) is designed to rationally control the orientation of bound PPL. The PPL orientation in the bidimensional confinement spacing alters relying on the PPL loading, with the majority of active sites facing the LDH layer at low PPL loading and facing the adjacent protein molecule at high PPL loading. The biocatalytic activity of the bound PPL significantly depends on its orientation. Remarkable enhancement of the bio-activity has been observed when the PPL/LDHNSs mass ratio is less than 9, and a maximum activity is met with at PPL/LDHNSs = 0.5. In addition, the thermal stability of PPL-LDHNSs bioactivity has been obviously improved in comparison with soluble PPL. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Propylene polymerization with nickel,diimine complexes containing pseudohalidesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2006Marcos L. Dias Abstract DADNiX2 nickel,diimine complexes [DAD = 2,6- iPr2C6H3NC(Me)C(Me)N2,6- iPr2C6H3] containing nonchelating pseudohalide ligands [X = isothiocyanate (NCS) for complex 1 and isoselenocyanate (NCSe) for complex 2] were synthesized, and the propylene polymerization with these complexes and also with the Br ligand (X = Br for complex 3) activated by methylaluminoxane (MAO) were investigated (systems 1, 2, and 3/MAO). The polypropylenes obtained with systems 1, 2, and 3 were amorphous polymers and had high molecular weights and narrow molecular weight distributions. Catalyst system 1 showed a relatively high activity even at a low Al/Ni ratio and reached the maximum activity at the molar ratio of Al/Ni = 500, unlike system 3. Increases in the reaction temperature and propylene pressure favored an increase in the catalytic activity. The spectra of polypropylenes looked like those of propylene,ethylene copolymers containing syndiotactic propylene and ethylene sequences. At the same temperature and pressure, system 2 presented the highest number of propylene sequences, and system 3 presented the lowest. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 458,466, 2006 [source] Purification and partial characterization of xyloglucan-hydrolyzing enzymes from watermelon placental tissueJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2009Yasar Karakurt Abstract BACKGROUND: Watermelon (Citrullus lanatus (Thunb.) Matsum & Nakai) fruit matrix glycans are comprised largely of xyloglucans (XGs). As in other fruits, these polymers show significant molecular mass downshifts during ripening. In the present study, we describe the purification and characteristics of a number of xyloglucanases (XGases) from the placental tissue of ripe watermelon. XGases were extracted from watermelon fruit placental tissue and purified by sequential ion-exchange, gel-permeation and concanavalin A chromatography. RESULTS: Five XGases (P1S2, P2S2, P3S1, P3S2, P3S3) were recovered with molecular masses ranging from 30.5 to 77.5 kDa on SDS-PAGE. All XGases showed maximum activity at pH 5,5.5 and 35,40 °C against tamarind seed XG and were also active against XG-rich matrix glycans from watermelon fruit. The enzymes were strongly inhibited by mercury and hydrolyzed XG without generation of oligomers or monomers. P3S3 had the highest activity against XG. The purified enzymes were active toward carboxymethylcellulose, indicating that they were not XG specific. CONCLUSION: The pattern of molecular mass downshifts during XG hydrolysis by the purified XGases and the absence of monomeric and oligomeric products are consistent with endo-type catalysis for the XGases and with a role for these enzymes in the degradation of cell wall XG during ethylene-induced watersoaking of watermelon fruit placental tissues. Copyright © 2009 Society of Chemical Industry [source] Conformational Study of Short Peptoid Models for Future Applications as Potent Antimicrobial CompoundsMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2007Fateh Singh Nandel Abstract Development of peptides as clinically useful drugs is limited by their poor metabolic stability and low bioavailability. Recent progresses in chemical synthesis and design have led to several strategies for producing potent mimetics. This study aims to analyze sequence/structure requirements and composition for antimicrobial peptoid designs, as use of peptoids is one of the most representative approaches to meet the goal of biomimicry. Analysis of the designs showed that for maximum activity and minimum hemolysis, the plane of the aromatic residues should be at an angle between 0 and 90,° with respect to membranes, cationic residues need not be at the terminal position, and central positions should be uniform in NIle, NLys, and NPhe residues. [source] Cytochrome b6f mutation specifically affects thermal dissipation of absorbed light energy in ArabidopsisTHE PLANT JOURNAL, Issue 3 2001Yuri Munekage Summary Light-induced lumenal acidification controls the efficiency of light harvesting by inducing thermal dissipation of excess absorbed light energy in photosystem II. We isolated an Arabidopsis mutant, pgr1 (proton gradient regulation), entirely lacking thermal dissipation, which was observed as little non-photochemical quenching of chlorophyll fluorescence. Map-based cloning showed that pgr1 had a point mutation in petC encoding the Rieske subunit of the cytochrome b6f complex. Although the electron transport rate was not affected at low light intensity, it was significantly restricted at high light intensity in pgr1, indicating that the lumenal acidification was not sufficient to induce thermal dissipation. This view was supported by (i) slow de-epoxidation of violaXanthin, which is closely related to lumenal acidification, and (ii) reduced 9-aminoacridine fluorescence quenching. Although lumenal acidification was insufficient to induce thermal dissipation, growth rate was not affected under low light growth conditions in pgr1. These results suggest that thermal dissipation is precisely regulated by lumenal pH to maintain maximum photosynthetic activity. We showed that pgr1 was sensitive to changes in light conditions, demonstrating that maximum activity of the cytochrome b6f complex is indispensable for short-term acclimation. [source] Heterologous expression and characterization of recombinant glycerol dehydratase from Klebsiella pneumoniae in Escherichia coliBIOTECHNOLOGY JOURNAL, Issue 6 2007Fenghuan Wang Abstract Glycerol dehydratase (EC 4.2.1.30), as one of the key enzymes in converting glycerol to the valuable intermediate 1,3-propanediol, is important for biochemical industry. The dhaB genes encoding coenzyme B12 -dependent glycerol dehydratase in Klebsiella pneumoniae were cloned and expressed in Escherichia coli. An effective co-expression system of multiple subunits protein was constructed. Heterologous expression vectors were constructed using the splicing by overlap extension-PCR technique to co-express the three subunits of the glycerol dehydratase. After induction by isopropyl-,- D -thiogalactopyranoside, SDS-PAGE analysis revealed that: (i) only the , subunit of glycerol dehydratase was expressed in direct expression system, (ii) the three subunits of glycerol dehydratase with predicted molecular massess of 64 (agr;), 22 (,), and 16 kDa (,) were expressed simultaneously in co-expression system, and (iii) the fusion expression system expressed the fusion protein of 99 kDa. Enzyme assay showed that the activities of three heterologous expression products were 27.4, 2.3, and 0.2 U/mg. The highest enzyme activity was almost 17 times of that in K. pneumoniae. The recombinant enzyme was purified and biochemically characterized. The apparent Km values of the enzyme for coenzyme B12 and 1, 2-propanediol were 8.5 nM and 1.2 mM, respectively. The enzyme showed maximum activity at pH 8.5 and 37°C. [source] Immobilization of a thermostable ,-amylase by covalent binding to an alginate matrix increases high temperature usabilityBIOTECHNOLOGY PROGRESS, Issue 2 2009Boon L. Tee Abstract Thermostable ,-amylase was covalently bound to calcium alginate matrix to be used for starch hydrolysis at liquefaction temperature of 95°C. 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride (EDAC) was used as crosslinker. EDAC reacts with the carboxylate groups on the calcium alginate matrix and the amine groups of the enzyme. Ethylenediamine tetraacetic acid (EDTA) treatment was applied to increase the number of available carboxylate groups on the calcium alginate matrix for EDAC binding. After the immobilization was completed, the beads were treated with 0.1 M calcium chloride solution to reinstate the bead mechanical strength. Enzyme loading efficiency, activity, and reusability of the immobilized ,-amylase were investigated. Covalently bound thermostable ,-amylase to calcium alginate produced a total of 53 g of starch degradation/mg of bound protein after seven consecutive starch hydrolysis cycles of 10 min each at 95°C in a stirred batch reactor. The free and covalently bound ,-amylase had maximum activity at pH 5.5 and 6.0, respectively. The Michaelis-Menten constant (Km) of the immobilized enzyme (0.98 mg/mL) was 2.5 times greater than that of the free enzyme (0.40 mg/mL). The maximum reaction rate (Vmax) of immobilized and free enzyme were determined to be 10.4-mg starch degraded/mL min mg bound protein and 25.7-mg starch degraded/mL min mg protein, respectively. The high cumulative activity and seven successive reuses obtained at liquefaction temperature make the covalently bound thermostable ,-amylase to calcium alginate matrix, a promising candidate for use in industrial starch hydrolysis process. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Characteristics of Immobilized Lipase on Hydrophobic Superparamagnetic Microspheres To Catalyze EsterificationBIOTECHNOLOGY PROGRESS, Issue 2 2004Zheng Guo A novel immobilized lipase (from Candida rugosa) on hydrophobic and superparamagnetic microspheres was prepared and used as a biocatalyst to catalyze esterification reactions in diverse solvents and reaction systems. The results showed that the immobilized lipase had over 2-fold higher activities in higher log P value solvents. An exponential increase of lipase activity against log P of two miscible solvent mixtures was observed for the first time. Both free and immobilized lipase achieved its maximum activity at the range of water activity ( aw) 0.5,0.8 or higher. At aw 0.6, the immobilized lipase exhibited markedly higher activities in heptane and a solvent-free system than did the native lipase. In multicompetitive reactions, the alcohol specificity of the lipase showed a strong chain-length dependency, and the immobilized enzyme exhibited more preference for a longer-chain alcohol, which is different from previous reports. The immobilized lipase showed higher specificities for butyric acid and the medium-chain-length fatty acids (C8,C12). Then, the immobilized lipase was extended to solvent-free synthesis of glycerides from glycerol and fatty acids. Recovered by magnetic separation, the immobilized lipase exhibited good reusability in repeated batch reaction, indicating its promising feature for biotechnology application. [source] | ||||||||||||||||