首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Alkaline proteases from the viscera of the striped seabream (Lithognathus mormyrus) were extracted and characterized. Interestingly, the crude enzyme was active over a wide range of pH from 6.0 to 11.0, with an optimum pH at the range of 8.0–10.0. In addition, the crude protease was stable over a broad pH range (5.0–12.0). The optimum temperature for enzyme activity was 50 °C. The crude alkaline proteases showed stability towards various surfactants and bleach agents and compatibility with some commercial detergents. It was stable towards several organic solvents and retained more than 50% of its original activity after 30 days of incubation at 30 °C in the presence of 25% (v/v) dimethyl sulfoxide, N,N-dimethylformamide, diethyl ether, and hexane. The crude enzyme extract was also tested for shrimp waste deproteinization in the preparation of chitin. The protein removal with a ratio enzyme/substrate of 10 was about 79%.  相似文献   

2.
Alkaline thiol protease named Prot 1 was isolated from a culture filtrate ofBotrytis cinerea. The enzyme was purified by ammonium sulfate fractionation, gel filtration, and ion-exchange chromatography. Thus, the enzyme was purified to homogeneity with specific activity of 30-fold higher than that of the crude broth. The purified alkaline protease has an apparent molecular mass of 43 kDa under denaturing conditions as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native molecular mass (45 kDa), determined by gel filtration, indicated that the alkaline protease has a monomeric form. The purified protease was biochemically characterized. The enzyme is active at alkaline pH and has a suitable and high thermostability. The optimal pH and temperature for activity were 9.0–10.0 and 60°C, respectively. This protease was stable between pH 5.0 and 12.0. The enzyme retained 85% of its activity by treatment at 50°C over 120 min; it maintained 50% of activity after 60 min of heating at 60°C. Furthermore, the protease retained almost complete activity after 4 wk storage at 25°C. The activity was significantly affected by thiol protease inhibitors, suggesting that the enzyme belongs to the alkaline thiol protease family. With the aim on industrial applications, we focused on studying the stability of the protease in several conditions. Prot 1 activity was not affected by ionic strength and different detergent additives, and, thus, the protease shows remarkable properties as a biodetergent catalyst.  相似文献   

3.
An organic solvent-stable protease from Pseudomonas aeruginosa PT121 was purified in a single step with 55% recovery by hydrophobic interaction chromatography on a Phenyl Sepharose High Performance matrix. The purified protease was homogenous on SDS-PAGE and had an estimated molecular mass of 33 kDa. The optimal pH and temperature conditions for enzyme activity were 8.0 and 60°C, respectively. The enzyme was classified as a metalloprotease based on its strong inhibition by EDTA and 1,10-phenanthroline and exhibited good stability across a broad pH range (6.0–11.0). The protease was quite stable in the presence of various water-miscible organic solvents. This is a unique property of the protease which makes it an ideal choice for application in aqueous-organic phase organic synthesis including peptides synthesis. The synthetic activity of the protease was tested using N-carbobenzoxy-l-asparagine (Z-Asp) and l-phenylalaninamide (Phe-NH2) as substrate in the presence of various water-miscible organic solvents for aspartame precursor synthesis. The highest yield was obtained in the presence of 50% DMSO (91%). The synthesis rate in the presence of DMSO was also much higher than the rates in the other tested organic solvents, and the initial rates of Z-Asp-Phe-NH2 synthesis in mixtures of various water-miscible organic solvents, with the exception of ethanol, correlated with the yields of Z-Asp-Phe-NH2. Furthermore, the PT121 protease was able to use various carboxyl components (Z-AA) and Phe-NH2 as substrates to catalyze the syntheses of the dipeptides, indicating that this protease has a broad specificity for carboxylic acid residue.  相似文献   

4.
Biochemical characterization of purified ANCUT2 cutinase from Aspergillus nidulans is described. The identified amino acid sequence differs from that predicted in Aspergillus genomic databases in amino acids not relevant for catalysis. The enzyme is thermo-alkaline, showing its maximum activity at pH 9 and 60 °C, and it retains more than 60% of its initial activity after incubation for 1 h at 60 °C for pH values between 6 and 10. ANCUT2 is more active towards long-chain esters and it hydrolyzes cutin; however, it also hydrolyzes short-chain esters. Cutinase is inhibited by metal ions, PMSF, SDS, and EDTA (10 mM). It retains 50% of its activity in most of the solvents tested, although it is more stable in hydrophobic solvents. According to its found biochemical properties, preliminary assays demonstrate its ability to synthesize methyl esters from sesame oil and the most likely application of this enzyme remains in detergent formulations.  相似文献   

5.
A protease from newly isolated Bacillus circulans M34 was purified by Q‐Sepharose anion exchange chromatography and Sepharose–bacitracin affinity chromatography followed by (NH4)2SO4 precipitation. The molecular mass of the purified enzyme was determined using SDS–PAGE. The optimum pH and temperature for protease activity were 11 and 50°C, respectively. The effect of various metal ions on protease activity was investigated. Alkaline protease from Bacillus circulans M34 wase activated by Zn2+, Cu2+ and Co2+ up to 31%. The purified protease was found to be stable in the organic solvents, surfactants and oxidizing agent. The substrate specificity of purified protease was investigated towards different substrates. The protease was almost completely inhibited by the serine protease inhibitor phenylmethanesulfonyl fluoride. The kinetic parameters of the purified protease, maximum rate (Vmax) and Michaelis constant (Km), were determined using a Lineweaver–Burk plot. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

6.
An alkaline protease producer haloalkaliphilic bacteria (isolate Vel) was isolated from west coast of India. It was related to Bacillus pseudofirmus on the basis of 16S r RNA gene sequencing, lipid profile and other biochemical properties. The protease secreted by this bacteria was purified 10-fold with 82% yield by a single step method on Phenyl Sepharose 6 Fast Flow column. The apparent molecular mass based on the sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was estimated to be 29 000 Da. The Km and Vmax towards caseinolytic activity were found to be 2 mg ml(-1) and 289.8 microg min(-1), respectively. The enzyme was active over the pH range of 8.5-12.0, the optimum being 10-11.0. The purified enzyme when kept at 45 degrees C and 50 degrees C for 40 min retained 92% and 85% protease activity, respectively. Effect of NaCl concentration on protease activity showed that the enzyme was slightly inhibited with high concentration of salt. The proteolytic activity was inhibited by PMSF, suggesting that the enzyme may belong to serine type protease. Interestingly, the activity was slightly enhanced with SDS (0.1%) and Triton X-100 (0.1%) but remained unaffected by Tween 80 (0.1%). The activity was affected by metal ions to varying extent. While Mn2+, Zn2+ and Mg2+ had no significant effect on protease activity, the enzyme was activated with Ca2+ (1 mM) and Cu2+ (5 mM). The stability of the enzyme in the presence of detergent components and surfactants is particularly attractive for its application in detergent industries.  相似文献   

7.
本文研究厌氧条件下产电绿脓杆菌P. aeruginosa BTE-1的电化学催化特征。研究结果表明,P. aeruginosa BTE-1菌株在厌氧条件下,不能分泌可充当电子介体的绿脓菌素,但可通过在电极表面形成生物膜呈现了直接电催化性能。P. aeruginosa BTE-1在电极表面形成生物膜与其在特定电极电位下向电极传递电子的过程直接相关,适宜的电位为+0.2 V (vs. SCE),电位过高可能会损害P. aeruginosa BTE-1细胞。室温范围内升高温度可增强P. aeruginosa BTE-1生物膜电催化活性,但过高的温度(>60℃)会抑制生物膜电催化活性。循环伏安曲线显示,在厌氧条件下形成的P. aeruginosa BTE-1生物膜,具有与典型产电菌株G. sulfurreducens相近的氧化还原电位(-0.4 V~ -0.2 V vs. SCE)。P. aeruginosa BTE-1生物膜可电催化酵母抽取物和葡萄糖,但不能电催化醋酸盐。  相似文献   

8.
Organic solvent-stable lipases have pronounced impact on industrial economy as they are involved in synthesis by esterification, interesterification, and transesterification. However, very few of such natural lipases have been isolated till date. A study of the recent past provided few pillars to rely on for this work. The three-dimensional structure, inclusive of the surface and active site, of 29 organic solvent-stable lipases was analyzed by subfamily classification and protein solvent molecular docking based on fast Fourier transform correlation approach. The observations revealed that organic solvent stability of lipases is their intrinsic property and unique with respect to each lipase. In this paper, factors like surface distribution of charged, hydrophobic, and neutral residues, interaction of solvents with catalytically immutable residues, and residues interacting with essential water molecules required for lipase activity, synergistically and by mutualism contribute to render a stable lipase organic solvent. The propensity of surface charge in relation to stability in organic solvents by establishing repulsive forces to exclude solvent molecules from interacting with the surface and prohibiting the same from gaining entry to the protein core, thus stabilizing the active conformation, is a new finding. It was also interesting to note that lipases having equivalent surface-exposed positive and negative residues were stable in a wide range of organic solvents, irrespective of their LogP values.  相似文献   

9.
Epoxy-activated monolithic CIM disks seem to be excellent supports for immobilization of protein ligands. The potential use of enzymes, immobilized on monolithic disks for rapid preparative cleavage proteins in solution was investigated. Digestion of complex plasma proteins was demonstrated by using inter-alpha inhibitors with elastase, immobilized on epoxy-activated CIM disks. Recently, a monoclonal antibody against human inter-alpha inhibitor proteins (MAb 69.31) was developed. MAb 69.31 blocks the inhibitory activity of inter-alpha inhibitor proteins to serine proteases. These results suggest that the epitope defined by this antibody is located within or proximal to the active site of the inhibitor molecule. This antibody, immobilized on monolithic disk, was used for very rapid isolation of inter-alpha proteins. The isolated complex protein was used for enzymatic digestion and isolation of cleavage products, especially from inter-alpha inhibitor light chain to elucidate precisely the target sequence for MAb 69.31 by N-terminal amino acid sequencing. Bovine pancreatic elastase immobilized on monolithic disk cleaves inter-alpha inhibitor protein complex into small fragments which are still reactive with MAb 69.31. One of these proteolytic fragments was isolated and partially sequenced. It could be shown that this sequence is located at the beginning of two proteinase inhibitor domains of the inter-alpha inhibitor light chain (bikunin). Elastase immobilized on monolithic disk offers a simple and rapid method for preparative isolation of protease cleavage fragments. The immobilized enzyme is stable and still active after repeated runs. A partial or complete digestion can be achieved by varying the flow rate.  相似文献   

10.
In silico analysis of keratinase Ker P from Pseudomonas aeruginosa revealed that its full gene of 1,497 bp constituted of a 72-bp signal sequence along with a long 520 bp pro-sequence and 905 bp core region. Position specific multiple sequence alignment of Ker P protein with other distant proteases revealed high variability within their N-terminal regions while the core protein was considerably conserved. Ker P (F1) and its four N-terminal truncations (F2-F5) lacking 72, 177, 405, 507 bp, respectively, were cloned and constitutively expressed as extracellular protein in pEZZ-18 secretory vector with Escherichia coli HB101 as the expression host. Ker P F1, Ker P F2, Ker P F3 and Ker P F4 products were active whereas no keratinolytic activity was obtained in Ker P F5. Further analysis revealed that only 187 bp pro-sequence region is required for correct folding of the protein into its active conformation and, thus, has chaperone-like activity. Further, comparative biochemical characterization revealed that the full-length keratinase Ker P F1 was catalytically more efficient than the truncated forms. Among the truncated enzymes, keratinase Ker P F4 exhibited better thermostability than Ker P F2 with a t(1/2) of >1 h at 60 °C. It also had a higher V (max) and K (m) on casein as compared with Ker P F2. However, no significant variation was observed with respect to kinetics on synthetic substrates.  相似文献   

11.
The current increase in amount of shrimp wastes produced by the shrimp industry has led to the need in finding new methods for shrimp wastes disposal. In this study, an extracellular organic solvent- and oxidant-stable metalloprotease was produced by Bacillus cereus SV1. Maximum protease activity (5,900 U/mL) was obtained when the strain was grown in medium containing 40 g/L shrimp wastes powder as a sole carbon source. The optimum pH, optimum temperature, pH stability, and thermal stability of the crude enzyme preparation were pH 8.0, 60 °C, pH 6–9.5, and <55 °C, respectively. The crude protease was extremely stable toward several organic solvents. No loss of activity was observed even after 60 days of incubation at 30 °C in the presence of 50% (v/v) dimethyl sulfoxide and ethyl ether; the enzyme retained more than 70% of its original activity in the presence of ethanol and N,N-dimethylformamide. The protease showed high stability toward anionic (SDS) and non-ionic (Tween 80, Tween 20, and Triton X-100) surfactants. Interestingly, the activity of the enzyme was significantly enhanced by oxidizing agents. In addition, the enzyme showed excellent compatibility with some commercial liquid detergents. The protease of B. cereus SV1, produced under the optimal culture conditions, was tested for shrimp waste deproteinization in the preparation of chitin. The protein removal with a ratio E/S of 20 was about 88%. The novelties of the SV1 protease include its high stability to organic solvents and surfactants. These unique properties make it an ideal choice for application in detergent formulations and enzymatic peptide synthesis. In addition, the enzyme may find potential applications in the deproteinization of shrimp wastes to produce chitin.  相似文献   

12.
A keratinolytic enzyme (KerA1) secreted by a newly isolated Bacillus pumilus strain A1 cultivated in medium containing chicken feather meal was purified and characterized, and the gene was isolated and sequenced. The molecular mass of the purified enzyme was estimated to be 34,000 Da by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and gel filtration. The optimum pH and temperature for the purified keratinase were 9.0 and 60 °C, respectively, using keratin as a substrate. KerA1 showed a high stability towards nonionic surfactants. It was found to be relatively stable toward the strong anionic surfactant (SDS). The deduced amino acid sequence of the keratinase KerA1 differs from both the organic solvent tolerant protease of B. pumilus 115b and the dehairing protease of B. pumilus UN-31-C-42 by one and nine amino acids, respectively. These results suggest that this keratinase may be a useful alternative and ecofriendly route for handling the abundant amount of waste feathers and for applications in detergent formulations.  相似文献   

13.
Commercially available aroma samples were evaluated for their olfactory quality by professional perfumers and tested for their antimicrobial activity. Agar diffusion and agar-dilution were used as test methods and a set of two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and four Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris G, Klebsiella pneumoniae and Salmonella abony) and a yeast, Candida albicans, were the test microorganisms. All the investigated compounds were active against Gram-positive bacteria, especially beta-caryophyllene against Enterococcus faecalis (MIC 6 ppm), but only few substances showed activity towards Gram-negative bacteria, except for cinnamic acid, which was active against all (MIC 60 ppm) and Candida albicans, against which cinnamic acid and caryophyllene oxide showed high activity (MIC < 60 ppm).  相似文献   

14.
A new organic solvent-tolerant strain Bacillus megaterium AU02 which secretes an organic solvent-tolerant protease was isolated from milk industry waste. Statistical methods were employed to achieve optimum protease production of 43.6 U/ml in shake flask cultures. The productivity of the protease was increased to 53 U/ml when cultivated under controlled conditions in a 7-L fermentor. The protease was purified to homogeneity by a three-step process with 24 % yield and specific activity of 5,375 U/mg. The molecular mass of the protease was found to be 59 kDa. The enzyme was active over a wide range of pH (6.0–9.0), with an optimum activity at pH 7.0 and temperature from 40 to 70 °C having an optimum activity at 50 °C. The thermal stability of the enzyme increased significantly in the presence of CaCl2, and it retained 90 % activity at 50 °C for 3 h. The K m and V max values were determined as 0.722 mg/ml and 0.018 U/mg respectively. The metalloprotease exhibited significant stability in the presence of organic solvents with log P values more than 2.5, nonionic detergents and oxidising agent. An attempt was made to test the synthesis of aspartame precursor (Cbz-Asp-Phe-NH2) which was catalysed by AU02 protease in the presence of 50 % DMSO. These properties of AU02 protease make it an ideal choice for enzymatic peptide synthesis in organic media.  相似文献   

15.
The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme's initial activity diminishes considerably after prolonged exposure to organic media. Studies geared towards understanding this last drawback have yielded unclear results. In the present work we decided to use electron paramagnetic resonance spectroscopy (EPR) to study the motion of an active site spin label (a nitroxide free radical) during 96 h of exposure of the serine protease subtilisin Carlsberg to four different organic solvents. Our EPR data shows a typical two component spectra that was quantified by the ratio of the anisotropic and isotropic signals. The isotropic component, associated with a mobile nitroxide free radical, increases during prolonged exposure to all solvents used in the study. The maximum increase (of 43%) was observed in 1,4-dioxane. Based on these and previous studies we suggest that prolonged exposure of the enzyme to these solvents provokes a cascade of events that could induce substrates to adopt different binding conformations. This is the first EPR study of the motion of an active-site spin label during prolonged exposure of an enzyme to organic solvents ever reported.  相似文献   

16.
In order to inhibit human leukocyte proteolytic activity as a means of arresting the inflammatory response in tissues in vivo, we have designed a novel antiprotease carrier named serumsomes. Stabilized human serum was added to a flask containing a film of dried, purified lipids (phosphatidylcholine/dicetyl phosphate/cholesterol, 70∶20∶10) and hand-shaken for 10 min. Equal volumes of human neutrophils, and either serumsomes (in stabilized human serum) or stabilized human serum alone were mixed together. Following 2 h of incubation at 37°C, the total elastase content of the neutrophils was reduced to 60±15% and 83±7% of the original activity by serumsomes and stabilized human serum, respectively. Analysis of β-glucuronidase activity, a nonproteolytic lysosomal marker enzyme, revealed no diminution of activity during either of these incubations. These experiments demonstrate that human neutrophils are capable of interacting with serumsomes in vitro, selectively inhibiting the lysosomal protease elastase. By administering serumsomes in vivo, one may potentially preload blood leukocytes with serum antiproteases prior to their migration to inflammatory sites and thus possibly reduce the extent of tissue injury.  相似文献   

17.
The genes of CS-2 lipase and its cognate foldase were cloned from Pseudomonas aeruginosa CS-2. A stop codon was not found in the lipase gene. The amino acid sequence deduced from the lipase gene from P. aeruginosa CS-2 showed 97.8%, 71.3%, and 71.2% identity with lipases from P. aeruginosa LST-03, P seudomonas mendocina ymp, and Pseudomonas stutzeri A1501, respectively. The co-expression of CS-2 lipase and its cognate foldase of P. aeruginosa CS-2 in E scherichia coli BL21 (DE3) resulted in the formation of a soluble lipase. The recombinant lipase and foldase were purified to homogeneity using nickel affinity chromatography and about 10.2-fold with 40.9% recovery was achieved for the purification of the recombinant lipase. The molecular masses of the lipase and the foldase were estimated to be 35.7 and 38.3 kDa in SDS-PAGE, respectively. The recombinant lipase showed stability in the presence of some organic solvents. The recombinant CS-2 lipase was immobilized and subsequently used for the synthesis of butyl acetate in heptane. The conversion of substrate decreased from 98.2% to 87.4% after 5 cycles in reuse of the immobilized lipase.  相似文献   

18.
The activity and kinetic stability of a keratinolytic subtilisin-like protease from Bacillus sp. P45 was investigated in 100 mM Tris-HCl buffer (pH 8.0; control) and in buffer with addition of Ca(2+) or Mg(2+) (1-10 mM), at different temperatures. Addition of 3 mM Ca(2+) or 4 mM Mg(2+) resulted in a 26% increment on enzyme activity towards azocasein when compared to the control (100%; without added Ca(2+) or Mg(2+)) at 55 °C. Optimal temperature for activity in the control (55 °C) was similar with Mg(2+); however, temperature optimum was increased to 60 °C with 3 mM Ca(2+), displaying an enhancement of 42% in comparison to the control at 55 °C. Stability of protease P45 in control buffer and with Mg(2+) addition was assayed at 40-50 °C, and at 55-62 °C with Ca(2+) addition. Data were fitted to six kinetic inactivation models, and a first-order equation was accepted as the best model to describe the inactivation of protease P45 with and without metal ions. The kinetic and thermodynamic parameters obtained showed the crucial role of calcium ions for enzyme stability. As biocatalyst stability is fundamental for commercial/industrial purposes, the stabilising effect of calcium could be exploited aiming the application of protease P45 in protein hydrolysis.  相似文献   

19.
The neutral mannan (WNM) and the acidic mannan (WAM025) fractions from baker's yeast (Saccharomyces cerevisiae) were found to manifest significant protective effects against intraperitoneal and intravenous infections of Listeria monocytogenes and Pseudomonas aeruginosa in mice. A remarkable decrease in the number of microbial cells in spleen and liver was observed in mice inoculated with these microorganisms after administration of either mannan fraction. In order to clarify the mechanism of the protective effects, we investigated in vitro the bactericidal activity and lysosomal enzyme activities such as myeloperoxidase, acid phosphatase, and neutral protease, in Kupffer cells (KCs) from mice pretreated with either mannan fraction. KCs from mice administered with these mannan fractions showed an enhanced killing effect on these bacteria in vitro, and neutral protease activity was considered to be one of the important factors in the killing effect on both L. monocytogenes and P. aeruginosa.  相似文献   

20.
The proteolytic activity produced by aBacillus subtilis isolated from a hot spring was investigated. Maximum protease production was obtained after 38 h of fermentation. Effects of various carbon and nitrogen sources indicate the requirement of starch and bacteriological peptone to be the best inducers for maximum protease production. Requirement for phosphorus was very evident, and the protease was secreted over a wide range of pH 5–11. The partially purified enzyme was stable at 60°C for 30 min. Calcium ions were effective in stabilizing the enzyme, especially at higher temperature. The enzyme was extremely salt tolerant and retained 100% activity in 5M NaCl over 96 h. The molecular weight of the purified enzymes as determined by SDS-PAGE was 28,000. The enzyme was completely inactivated by PMSF, but little affected by urea, sodium dodecyl sulfate, and sodium tripoly phosphate.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号