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1.
We developed a method using nitrocellulose membranes and image analysis to localise and quantify acid phosphatase activity in the rhizosphere of two plant species, one with cluster roots (Dryandra sessilis (Knight) Domin) and another with ectomycorrhizal roots (Pinus taeda L.). Membranes were placed in contact with roots and then treated with a solution of x, α-naphthyl phosphate and Fast Red TR. Acid phosphatase activity was visualised as a red imprint on the membrane. We quantified acid phosphatase activity by image analysis of scanned imprints. The method was used to estimate the spatial distribution of acid phosphatase activity within particular root classes (lateral roots, mycorrhizal roots, root clusters). Over 95% of the acid phosphatase activity of the root system of D. sessilis was associated with cluster roots, and between 20 and 32% of the root surface active. About 26 % of the acid phosphatase activity of the root system of P. taeda was associated with mycorrhizal roots and unsuberised white root tips and less than 10% of the root surface was active, irrespective of root type. This non-destructive method can be used for rapid, semi-quantitative assessment of acid phosphatase activity in the laboratory and in situ. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

2.
Phenylboronates are competitive inhibitors of serine hydrolases including lipases. We studied the effect of m-aminophenylboronate on triglyceride-hydrolyzing activity of hepatic lipase (EC 3.1.1.3). m-Aminophenylbo ronate inhibited hepatic lipase activity with a K1 value of 55 μM. Furthermore, m-aminophenylboronate protected hepatic lipase activity from inhibition by di-isopropyl fluorophosphate, an irreversible active site inhibitor of serine hydrolases. Inhibition of hepatic lipase activity by m-aminophenylboronate was pH-dependent. The inhibition was maximal at pH 7.5, while at pH 10 it was almost non-existent. These data were used to develop a purification procedure for postheparin plasma hepatic lipase and lipoprotein lipase. The method is a combination of m-aminophenylboronate and heparin-Sepharose affinity chromatographies. Hepatic lipase was purified to homogeneity as analyzed on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The specific activity of purified hepatic lipase was 5.46 mmol free fatty acids h−1 mg−1 protein with a total purification factor of 14 400 and a final recovery of approximately 20%. The recovery of hepatic lipase activity in m-aminophenylboronate affinity chromatography step was 95%. The purified lipoprotein lipase was a homogeneous protein with a specific activity of 8.27 mmol free fatty acids h−1 mg−1 The purification factor was 23 400 and the final recovery approximately 20%. The recovery of lipoprotein lipase activity in the m-aminophenylboronate affinity chromatography step was 87%. The phenylboronate affinity chromatography step can be used for purification of serine hydrolases which interact with boronates.  相似文献   

3.
A novel pyrroloquinoline quinone dependent glucose dehydrogenase like enzyme (PQQ GDH) was isolated from Sorangium cellulosum So ce56. The putative coding region was cloned, over expressed in E. coli and the resulting enzyme was characterized. The recombinant protein has a relative molecular mass of 63 kDa and shows 43% homology to PQQ GDH-B from Acinetobacter calcoaceticus. In the presence of PQQ and CaCl2 the enzyme has dehydrogenase activity with the substrate glucose as well as with other mono- and disaccharides. The thermal stability and its pH activity profile mark the enzyme as a potential glucose biosensor enzyme. In order to decrease the activity on maltose, which is unwanted for a potential application in biosensors, the protein was rationally modified at three specified positions. The best variant showed a 59% reduction in activity on maltose compared to the wild type enzyme. The catalytic efficiency (k cat/K M) was reduced fivefold but the specific activity still amounted to 63% of the wild type activity.  相似文献   

4.
In the present study, metagenomic library of Western Ghats soil sample was constructed in a fosmid vector (pCC1FOS) and screened for biocatalytic properties. The clones showed amylolytic activity on Luria-Bertani starch agar plates and one of them was studied in detail. The enzyme exhibited stability at elevated temperature with 60°C being the optimal temperature. The enzyme retained more than 30% activity after 60 min incubation at 80°C. It also showed more than 70% activity retention in 1.5 M NaCl solution. The pH optimum of the enzyme was at pH = 5.0. The enzyme possesses good activity in the presence of chelating and strong reducing agents with activity enhancements or retention being observed at 5 mM β-mercaptoethanol, dithiothreitol and N-bromosuccinimide. However, almost complete loss of activity was observed with 5 mM EDTA, while activity enhancement was observed upon incubation with Ca2+ suggesting it to be a Ca2+-dependent α-amylase, which was further confirmed by a thin-layer chromatography (TLC). The TLC run revealed that digestion pattern was similar to commercial α-amylase. The 16S rRNA gene sequence (GenBank accession number HQ680979) BLAST showed 95% similarities with Exiguobacterium sp. AFB-11 and AFB 18, with query sequence coverage of 99%.  相似文献   

5.
The response of glycolate oxidase from shoots of Salicornia europaea L. and from leaves of Pisum sativum L. to salt treatment during assay was studied by DCPIP reduction and O2 uptake. In Pisum there was found up to five times more glycolate oxidase activity per gram fresh weight than in Salicornia. However, the calculation of the specific activity pointed out that this result was caused only by the high level of enzyme protein in Pisum, and that specific activity from both species was of equal size. By the DCPIP method it was shown that in test media containing up to 1.0 M NaCl or KCl glycolate oxidase of Salicornia was of equal size compared with the control (medium without additional salts). With 2.0 M NaCl or KCl the activity decreased by about 80 and 30% respectively. Glycolate oxidase of Pisum was somewhat more salt sensitive. 1.0 M NaCl or KCl reduced the activity by about 35%. In the presence of 2.0 M NaCl or KCl the enzyme activity from Pisum was inhibited to about 80 and 60% respectively. By substituting sulfates for chlorides the activity of glycolate oxidase from both Salicornia and Pisum was stimulated strongly. 1.5 M Na2SO4 and 0.5 M K2SO4 (both are saturated solutions) caused an increase of glycolate activity from Salicornia of about 225 and 185% respectively, and from Pisum of about 50 and 30% respectively. Studying the response of glycolate oxidase to salt treatment by O2 uptake one must establish that with this method the degree of inhibition of enzyme activity at higher salt concentrations was always more severe than with dye reduction. Addition of 1.0 M NaCl or KCl to the assay medium caused an inhibition of glycolate oxidase activity from Salicornia of about 50% and from Pisum of about 60%. 2.0 M NaCl or KCl reduced the enzyme activity of both Salicornia and Pisum to nearly 10% of control activity. Furthermore, in contrast to DCPIP reduction no stimulating effect of sulfates on glycolate oxidase activity was detectable. Indeed, the inhibitory effect of sulfates was very slight. 1.0 M Na2SO4 caused a mean inhibition of glycolate oxidase activity of only 15% with both species, and in the presence of 1.5 M Na2SO4 50% of control activity was measured. At maximal K2SO4 concentrations (0.5 M) glycolate oxidase from both Salicornia and Pisum was also unaffected. It is supposed that the described salt tolerance of glycolate oxidase in vitro, possibly is due to an adaptation of the enzyme to high salt levels within peroxisomes in vivo.  相似文献   

6.
Kelp grouper, Epinephelus bruneus, fed for 30 days with 0% (control), 0.1%, 1.0%, and 2.0% of Styrax japonica supplementation diets, led to reductions in mortality after being challenged with a bacterium (Vibrio harveyi) and a ciliate protozoan (Uronema marinum). The enriched diets significantly increased the survival rate as compared to the controls. The phagocytic and respiratory activities were significantly increased in kelp groupers given 1.0% and 2.0% enriched diets. The complement activity, lysozyme activity, serum bactericidal activity, and total protein level significantly increased with any enriched diet against the pathogens; however antiprotease activity and myeloperoxidase levels significantly increased only with 1.0% and 2.0% enriched diets while the α2-macroglobulin level was significantly enhanced with 1.0% enriched diet. The study suggests that incorporation of S. japonica at 1.0% and 2.0% level in the diet significantly enhances the immune responses in the kelp grouper E. bruneus against V. harveyi and U. marinum.  相似文献   

7.
Glutaminase from Stenotrophomonas maltophilia NYW-81 was purified to homogeneity with a final specific activity of 325 U/mg. The molecular mass of the native enzyme was estimated to be 41 kDa by gel filtration. A subunit molecular mass of 36 kDa was measured with SDS-PAGE, thus indicating that the native enzyme is a monomer. The N-terminal amino acid sequence of the enzyme was determined to be KEAETQQKLANVVILATGGTIA. Besides l-glutamine, which was hydrolyzed with the highest specific activity (100%), l-asparagine (74%), d-glutamine (75%), and d-asparagine (67%) were also hydrolyzed. The pH and temperature optima were 9.0 and approximately 60°C, respectively. The enzyme was most stable at pH 8.0 and was highly stable (relative activities from 60 to 80%) over a wide pH range (5.0–10.0). About 70 and 50% of enzyme activity was retained even after treatment at 60 and 70°C, respectively, for 10 min. The enzyme showed high activity (86% of the original activity) in the presence of 16% NaCl. These results indicate that this enzyme has a higher salt tolerance and thermal stability than bacterial glutaminases that have been reported so far. In a model reaction of Japanese soy sauce fermentation, glutaminase from S. maltophilia exhibited high ability in the production of glutamic acid compared with glutaminases from Aspergillus oryzae, Escherichia coli, Pseudomonas citronellolis, and Micrococcus luteus, indicating that this enzyme is suitable for application in Japanese soy sauce fermentation.  相似文献   

8.
The activities of the enzymes α‐ and β‐glucosidase, and leucine aminopeptidase were measured in cultures of the dinoflagellate Prorocentrum minimum (Pavill.) J. Schiller and in field samples collected during dinoflagellate blooms occurring in tributaries of the Chesapeake Bay, Maryland, USA. Activities were measured using fluorogenic artificial substrates and partitioned among the >5 μm size fraction, small microbes fraction (0.1–5 μm), and dissolved phase (<0.1 μm). P. minimum and most other photosynthetic dinoflagellates are >5 μm in size and thus can be separated from the small microbes fraction, which contains most bacteria. Little to no glucosidase activity was detected associated with the >5 μm size fraction in cultures or in field samples, with most of the activity (67% to 93% in cultures, 54% to 100% in field samples) in the small microbes size fraction for both α and β glucosidase. In contrast, 67% to 90% of the total leucine aminopeptidase (LAP) activity in cultures was measured in the >5 μm fraction. Within a culture, LAP activity in the size fraction containing P. minimum decreased in response to ammonium and urea additions, but not in response to nitrate. In field samples, LAP activity was positively correlated with dinoflagellate abundance and chl a, and negatively correlated with ammonium concentration. During blooms, up to 34% of LAP activity was associated with the >5 μm fraction, indicating that when abundant, dinoflagellates may make a substantial contribution to ectocellular LAP activity in the water column.  相似文献   

9.
Indiscriminate use of synthetic pesticides to control the pests causes negative effects on non-target organisms. Some of the chemicals under B and C categories are carcinogenic to humans. The present study was aimed to assess the antifeedant, larvicidal and pupicidal activities of Hygrophila schulii (syn. H. auriculata) and Blumea mollis against Helicoverpa armigera. Maximum antifeedant activity of 70.01% was observed in ethyl acetate extract of H. schulii at 5.0% concentration with LC50 value of 2.0%. B. mollis ethyl acetate extract at 5.0% concentration showed antifeedant activity of 35.40% with LC50 value of 8.38%. The data for antifeedant activity showed homogeneity of variances in Levene Statistics and normality in Shapiro–Wilk test. Ethyl acetate extract of H. schulii at 5.0% concentration showed 68.66% larvicidal activity with LC50 value of 2.97%. It also showed 73.33% pupicidal activity and was statistically significant from other treatments. No pupicidal activity was observed in ethyl acetate extract of B. mollis. All concentrations of ethyl acetate extract of H. schulii showed promising biological activities which differed statistically from other treatments. Ethyl acetate extract of H. schulii could be used to develop new botanical formulations to manage agricultural pests.  相似文献   

10.
Strains of thermophilic bacilli were screened for cellulolytic activity by gel diffusion assay on selective medium at 55°C. Strain B-41361, identified as a strain of Bacillus licheniformis, displayed activity against carboxymethylcellulose. Zymogram analysis demonstrated several catalytically active polypeptides with the most prominent species having a mass of 37 kDa. The enzyme was purified 60-fold with a 17% yield and specific activity of 183 U/mg. The amino terminal sequence was homologous to members of glycoside hydrolase family 5. Optimal temperature was 65°C (measured over 30 min), but the enzyme was most stable at 60°C, retaining greater than 90% activity after one hour. The enzyme had a broad pH range, with maximal activity at pH 6.0, 75% maximal activity at pH 4.5, and 40% at pH 10. The enzyme hydrolyzed p-nitrophenylcellobioside, barley β-glucan, and lichenan, but no activity was detected against avicel or acid-swollen cellulose.Mention of a trade name or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.  相似文献   

11.
A Perigo-type antibacterial factor (PTF) was produced when tryptone (a pancreatic digest of casein) medium was heated with nitrite at 121°C for 20 min. This PTF was inhibitory against Staphylococcus aureus, Bacillus subtilis and Clostridium botulinum, but was not against Escherichia coli and Salmonella typhimurium. The inhibitory activity varied with the concentration of nitrite (5 ~ 100 ppm) and tryptone (1, 2, 4%), and with pH (4, 5, 6, 7). The maximum inhibitory activity was observed when the medium containing 4% tryptone and 0.2% thioglycolate was heated with more than 50 ppm nitrite at pH 6. The tryptone was separated into three fractions by gel filtration and PTF was produced in every fraction, although the inhibitory activity was different in each. Our PTF might be unstable towards oxygen because its activity was lost completely by shaking for more than 16 hr.  相似文献   

12.
Zhang J  Liu J  Zhou J  Ren Y  Dai X  Xiang H 《Biotechnology letters》2003,25(17):1463-1467
The lipA gene encoding a thermostable esterase was cloned from Thermoanaerobacter tengcongensis and overexpressed in Escherichia coli. The recombinant esterase, with a molecular mass of approx. 43 kDa determined by SDS-PAGE, was purified to homogeneity through Sephadex G-100 gel filtration. The purified enzyme actively hydrolyzed tributyrin but not olive oil. Maximum activity was observed on p-nitrophenyl (NP)-propionate (C3) and p-NP-butyrate (C4), with little activity towards p-NP-palmitate (C16). The esterase was optimally active at 70 °C (over 15 min) and at pH 9. It is highly thermostable, with a residual activity greater than 80% after incubation at 50 °C for more than 10 h. The activity was not inhibited by 5 mM EDTA and PMSF, indicating the esterase is not a metalloenzyme and may contain a specific structure around the catalytic serine residue. In addition, it was stable for 1 h at 37 °C in 1% CHAPS and Triton X-100 but not stable in 1% Tween 20 or SDS.  相似文献   

13.
—UDP-galactose:ceramide galactosyltransferase (CGalT) (E.C. 2.4.1.62) and UDP-glucose:ceramide glucosyltransferase (CGlcT) activities were measured in myelinating cultures of newborn rat cerebellum. Specific activities were measured at various days in vitro and the pattern of activities compared with that reported for in vivo tissue. Cultures demyelinated by incubation with media containing 22% serum from rabbits in which experimental allergic encephalomyelitis (EAE) was induced by injection with whole guinea-pig spinal cord, had 28% of CGalT specific activity and 86% of CGlcT specific activity measured in control cultures. Cultures in which myelination was inhibited by maintenance on media containing 0.15 mm -5-bromo-2′-deoxyuridine (BUdR) had 10% of CGalT specific activity and 118% of CGlcT specific activity of control cultures. Cultures in which myelination was inhibited by maintenance on media containing 2% EAE serum had 12% of the CGalT specific activity of control cultures. The data suggest that in vitro CGalT is predominantly a glial enzyme while CGlcT occurs primarily in neurons, and that the reduced CGalT activity may be involved in the mechanism of myelination inhibition by BUdR and by EAE serum.  相似文献   

14.
Objective: To study the effect of dietary weight loss, postural change, and an oral glucose load on serum angiotensin-converting enzyme (ACE) activity in obese adults. Research Methods and Procedures: Sixteen obese adult men and women with a mean body mass index of 35.7 ± 4.3 kg/m2 were studied after 1 week on a maintenance energy lead-in diet and after 5 weeks on an identical but 40% reduced-energy diet provided by the General Clinical Research Center (GCRC). ACE activity was measured spectrophotometrically. Plasma renin activity and serum aldosterone were measured by radioimmunoassay. Results: All subjects lost weight, with a mean decrease in body weight of 7.0 ± 2.1 kg or 6 ± 3% of initial body weight (p < 0.00001). Systolic and diastolic blood pressure, supine plasma renin activity, and serum aldosterone levels decreased with weight loss (p < 0.05). Supine ACE activity decreased 23 ± 12% with weight loss (p < 0.00001). Standing ACE activity, which was significantly higher than supine ACE activity before and after weight loss (p < 0.05), also decreased 18 ± 17% with weight loss (p = 0.0007). A 75-g oral glucose load had no effect on serum ACE activity over a 3-hour period. Discussion: In obese adults, serum ACE activity declines with modest weight loss, increases with postural change, and is unaffected by an oral glucose load.  相似文献   

15.
Microsomal and supernatant chitinase activities have been prepared from mycelial cultures ofMucor mucedo. Studies of their responses to changing temperature and phospholipid composition indicate that the lipid environment is important in regulating membrane-bound chitinase activity, but that supernatant chitinase activity does not have a phospholipid requirement. Membrane-bound chitinase was solubilized by different types of non-denaturing detergents. Maximum solubilization was achieved with 1 mM Zwittergent-14 or 1.2% Triton X-100 (93% and 90% solubilization, respectively). This solubilized chitinase activity could not be activated by protease treatment, i.e., was nonzymogenic, as was the supernatant chitinase. The insoluble residual chitinase activity was, however, zymogenic after treatment with 1.2% Triton X-100, but fully active after treatment with 3% Triton X-100.  相似文献   

16.
The essential oil obtained by hydrodistillation from the aerial parts of Aristolochia delavayi Franch. (Aristolochiaceae), a unique edible aromatic plant consumed by the Nakhi (Naxi) people in Yunnan, China, was investigated using GC/MS analysis. In total, 95 components, representing more than 95% of the oil composition, were identified, and the main constituents found were (E)‐dec‐2‐enal (52.0%), (E)‐dodec‐2‐enal (6.8%), dodecanal (3.35%), heptanal (2.88%), and decanal (2.63%). The essential oil showed strong inhibitory activity (96% reduction) of the production of bacterial volatile sulfide compounds (VSC) by Klebsiella pneumoniae, an effect that was comparable with that of the reference compound citral (91% reduction). Moreover, the antimicrobial activity of the essential oil and the isolated major compound against eight bacterial and six fungal strains were evaluated. The essential oil showed significant antibacterial activity against Providencia stuartii and Escherichia coli, with minimal inhibitory concentrations (MIC) ranging from 3.9 to 62.5 μg/ml. The oil also showed strong inhibitory activity against the fungal strains Trichophyton ajelloi, Trichophyton terrestre, Candida glabrata, Candida guilliermondii, and Cryptococcus neoformans, with MIC values ranging from 3.9 to 31.25 μg/ml, while (E)‐dec‐2‐enal presented a lower antifungal activity than the essential oil.  相似文献   

17.
The objective of this study was to characterize the extracellular proteolytic activity of Streptococcus bovis. Strains KEG, JB1, NCFB 2476, and K11.21.09.6C produced very similar large molecular weight (160–200 kDa) extracellular proteases that were specifically inhibited by PMSF, a serine protease inhibitor. Further experiments with S. bovis KEG indicated that cultures grown with casein as the sole added N source produced the greatest level of proteolytic activity, and the level of proteolytic activity was independent of growth rate. Clarified ruminal fluid (CRF) decreased proteolytic activity by 54% compared with cultures grown with casein alone, and addition of exogenous peptides and carbohydrates (CHO) to the CRF further reduced the level of proteolytic activity by 44% and 52%, respectively. These results suggested that the proteolytic activity of S. bovis KEG was modulated by available N source and that the proteolytic activity was present for reasons other than providing N for growth. The role of S. bovis in ruminal proteolysis requires further definition, but phenotypic similarity among some ruminal strains would suggest a common niche in ruminal proteolysis. The uniformity of proteolytic activities could make S. bovis a prime candidate for manipulation in ruminal proteolysis control strategies. Received: 12 January 1999 / Accepted: 19 May 1999  相似文献   

18.
The aim of this study was to determine the in vitro fungicidal and growth inhibitory activity of ciclopirox olamine alone (1% and 1.5%) or in association with 1% zinc pyrithione compared to 2% ketoconazole, against Malassezia species particularly involved in the pathogenesis of seborrheic dermatitis. Experiments were performed on Malassezia globosa IP 2387.96 and M. restricta IP 2392.96 strains. Growth inhibitory activity of the active compounds in solution was evaluated by measuring minimal inhibitory concentrations using a broth micro-method and their fungicidal activity by a filtration method after contact times between solutions and yeasts ranging from 3–5 to 30 min. Concerning the determination of minimal inhibitory concentration of ciclopirox olamine/zinc pyrithione, it revealed the marked synergistic inhibitory effect of the association, leading to a higher efficacy compared to ketoconazole. As to the fungicidal activity of ciclopirox olamine, it significantly increased with the contact time. After 15–30 min of contact between 1.5% ciclopirox olamine and Malassezia strains, a 2-log reduction of Malassezia counts was observed. The 1.5% ciclopirox olamine/1% zinc pyrithione association was characterized by a steady fungicidal efficacy whereas the 2% ketoconazole solution did not express any fungicidal effect. In conclusion, this study demonstrates the in vitro inhibitory and fungicidal efficacy of the ciclopirox olamine/zinc pyrithione association against Malassezia species and underscores its potential interest in the treatment of seborrheic dermatitis.  相似文献   

19.
A triple-point mutated fish microsomal epoxide hydrolase (mEH) gene from Mugil cephalus was expressed in Escherichia coli in the presence of various chaperones to prevent protein aggregations. The enantioselective hydrolytic activity was more than doubled by co-expressing the EH mutant gene with pGro7 plasmid. The highly active EH mutant with a his-tag was immobilized onto magnetic silica assembled with NiO nanoparticles. The immobilized mEH mutant was re-used more than 10 times with less than 10% activity loss. (S)-Styrene oxide with 98% enantiopurity was repeatedly obtained with over 50% of the theoretical yield by the magnetically separable high-performance mEH mutant.  相似文献   

20.
Abstract

The laccase (Lac), manganese peroxidases (MnP), and lignin peroxidase enzymes produced by basidiomycete have been studied due to their potential in bioremediation, therefore, in this study, degradation of diclofenac (DCF), sulfamethoxazole (SMX), indomethacin (IND), gemfibrozil (GFB), and bezafibrate (BZF) by enzymes produced by Trametes maxima, Pleurotus sp., and Pycnosporus sanguineus grown in culture was evaluated. The degradation of drugs can mainly be attributed to MnP because a correlation between the activity of this enzyme and the degree of removal was found. The specific activity of Lac did not show correlation with drug removal, while lignin peroxidase was not expressed. Trametes maxima showed the highest specific activity of MnP (387.6?±?67.4?U/mg) and efficiency removal 90.2% of DCF, 72.62% of SMX, 60.76% of IND, 43.39% of GFB, and 32.59% of BZF) followed by Pleurotus sp. with specific activity of MnP of 55.9?±?8.5?U/mg and 89.47% of DCF, 47.61% of GFB and 73% of IND were removed, P. sanguineus had the lowest specific activity of 18?±?1.3?U/mg and was able to remove only 42% of SMX and 10.59% of IND. In order to prove that MnP remove drugs instead of Lac, the pure Lac was tested and only degraded DCF.  相似文献   

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