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41.
Hossnieh Kafshdar Jalali Abdolreza Salamatzadeh Arezou Kafshdar Jalali Hamed Haddad Kashani Salman Ahmadi Asbchin Khosro Issazadeh 《Probiotics and antimicrobial proteins》2016,8(1):41-45
The main drawback of current antibiotic therapies is the emergence and rapid increase in antibiotic resistance. Nocardiae are aerobic, Gram-positive, catalase-positive, non-motile actinomycetes. Nocardia brasiliensis was reported as antibiotic producer. The purpose of the study was to determine antibacterial activity of N. brasiliensis PTCC 1422 against isolated Enterobacteriaceae from urinary tract infections (UTIs). The common bacteria from UTIs were isolated from hospital samples. Antimicrobial susceptibility test was performed for the isolated pathogens using Kirby–Bauer disk diffusion method according to clinical and Laboratory Standards Institute guideline. Antagonistic activity of N. brasiliensis PTCC 1422 was examined with well diffusion methods. Supernatant of N. brasiliensis PTCC 1422 by submerged culture was analyzed with gas chromatography–mass spectrometry. Isolated strains included Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Proteus mirabilis. The most common pathogen isolated was E. coli (72.5 %). Bacterial isolates revealed the presence of high levels of antimicrobial resistances to ceftriaxone and low levels of resistance to cephalexin. Supernatant of N. brasiliensis PTCC 1422 showed antibacterial activity against all of the isolated microorganisms in well diffusion method. The antibiotic resistance among the uropathogens is an evolving process, so a routine surveillance to monitor the etiologic agents of UTI and the resistance pattern should be carried out timely to choose the most effective empirical treatment by the physicians. Our present investigation indicates that the substances present in the N. brasiliensis PTCC 1422 could be used to inhibit the growth of human pathogen. Antibacterial resistance among bacterial uropathogen is an evolving process. Therefore, in the field on the need of re-evaluation of empirical treatment of UTIs, our present. The study has demonstrated that N. brasiliensis PTCC 1422 has a high potential for the treatment of UTIs. 相似文献
42.
Maryam Siroosi Mohammad Ali Amoozegar Khosro Khajeh Mostafa Fazeli Mehran Habibi Rezaei 《Extremophiles : life under extreme conditions》2014,18(1):25-33
A halophilic archaeon, Halorubrum sp. strain Ha25, produced extracellular halophilic organic solvent-tolerant amylopullulanase. The maximum enzyme production was at high salt concentration, 3–4 M NaCl. Optimum pH and temperature for enzyme production were 7.0 and 40 °C, respectively. Molecular mass of purified enzyme was estimated to be about 140 kDa by SDS–PAGE. This enzyme was active on pullulan and starch as substrates. The apparent K m for the enzyme activity on pullulan was 4 mg/ml and for soluble starch was 1.8 mg/ml. Optimum temperature for amylolytic and pullulytic activities was 50 °C. Optimum pH for amylolytic activity was 7 and for pullulytic activity was 7.5. This enzyme was active over a wide range of concentrations (0–4.5 M) of NaCl. The effect of organic solvents on the enzyme activities showed that this enzyme was more stable in the presence of non-polar organic solvents than polar solvents. This study is the first report on amylopullulanase production in halophilic bacteria and archaea. 相似文献
43.
Mahdi Mohammadian Mehrnoosh Fathi-Roudsari Nasrin Mollania Arastoo Badoei-Dalfard Khosro Khajeh 《Journal of industrial microbiology & biotechnology》2010,37(8):863-869
Laccases (benzenediol oxygen oxidoreductase; EC 1.10.3.2) have many biotechnological applications because of their oxidation
ability towards a wide range of phenolic compounds. Within recent years, researchers have been highly interested in the identification
and characterization of laccases from bacterial sources. In this study, we have isolated and cloned a gene encoding laccase
(CotA) from Bacillus sp. HR03 and then expressed it under microaerobic conditions and decreased temperature in order to obtain high amounts of
soluble protein. The laccase was purified and its biochemical properties were investigated using three common laccase substrates,
2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), syringaldazine (SGZ) and 2,6-dimethoxyphenol (2,6-DMP). K
M and k
cat were calculated 535 μM and 127 s−1 for ABTS, 53 μM and 3 s−1 for 2, 6-DMP and 5 μM and 20 s−1 for SGZ when the whole reactions were carried out at room temperature. Laccase activity was also studied when the enzyme
was preincubated at 70 and 80°C. With SGZ as the substrate, the activity was increased three-fold after 50 min preincubation
at 70°C and 2.4-fold after 10 min preincubation at 80°C. Preincubation of the enzyme in 70°C for 30 min raised the activity
four-fold with ABTS as the substrate. Also, l-dopa was used as a substrate. The enzyme was able to oxidize l-dopa with the K
M and k
cat of 1,493 μM and 194 s−1, respectively. 相似文献
44.
Mahmoud Shavandi Majid Sadeghizadeh Khosro Khajeh Ghasemali Mohebali Alireza Zomorodipour 《Applied microbiology and biotechnology》2010,87(4):1455-1461
The bacterium Gordonia alkanivorans RIPI90A has been previously reported as dibenzothiophene-desulfurizing strain. The present study provides a complete investigation
of the dsz operon including dsz promoter analysis from desulfurization competent strain belonging to the genus Gordonia. PCR was used to amplify the dszABC genes and adaptor ligation-based PCR-walking strategy used to isolate the dsz promoter. Unlike the dsz operon of Rhodococcus erythropolis, the operon of RIPI90A was located on chromosome. Despite the remarkably high homology between dsz genes of G. alkanivorans RIPI90A and R. erythropolis IGST8, promoter sequences of the strains were not very similar. The dsz promoter of G. alkanivorans RIPI90A shows only 52.5% homology to that of R. erythropolis IGTS8 and Gordonia nitida. Deletion analysis of the dsz promoter from RIPI90A using luciferase as a reporter gene revealed that the dsz promoter was located in regions from −156 to −50. 相似文献
45.
Gholivand K Shariatinia Z Khajeh K Naderimanesh H 《Journal of enzyme inhibition and medicinal chemistry》2006,21(1):31-35
The ability of phosphoramidates Me2NP(O)(Cl)(p-NHC6H4NO2) 1, Me2NP(O)(p-NHC6H4NO2)2 2, (CH3C6H4O-p)P(O)(p-NHC6H4NO2)2 3 and (CH3C6H40-p)2P(O)(p-NHC6H4NO2) 4 to inhibit human acetylcholinesterase (hAChE) has been evaluated by a modified Ellman's method and spectrophotometric measurements. Results showed that compounds 1 and 2 do not have any inhibitory potency, whereas compounds 3 and 4 were reversible mixed inhibitors. The IC50 values for inhibitors 3 and 4 were 0.143 and 0.581 mM, respectively. The previously unknown compounds 3 and 4 were synthesized and characterized by 1H, 13C, 31P NMR and IR spectroscopy and elemental analysis. 相似文献
46.
Khodayar Gholivand Ahlam Madani Alizadegan Azam Anaraki Firooz Khosro Khajeh Hossein Naderi-manesh Hamidreza Bijanzadeh 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):105-111
Carbacylamidophosphates with the general formula RC(O)NHP(O)R1R2 constitute organophosphorus compounds that are used as insecticides, pesticides and ureas inhibitors. In this work, we studied the inhibition potency of CCl3C(O)NHP(O)Cl21, CHCl2C(O)NHP(O)Cl22, CH2ClC(O)NHP(O)Cl23 and CF3C(O)NHP(O)Cl24, which are the major intermediates for carbacylamidophosphates synthesis towards human erythrocyte acetylcholinesterase (hAChe) activity using Ellman's modified kinetic method. Unexpectedly, it was observed that they were not only hydrolytically unstable but also inhibited hAChE in a similar manner to that produced by organophosphorus insecticides. Enzymatic data, bimolecular inhibition rate constants (ki) and IC50 values for inhibition of hAChE demonstrated that they are irreversible inhibitors and the inhibition potency of compound 2 (IC50 = 88 μM) was the greatest in comparison with compounds 1, 3 and 4. Also the electropositivity of the phosphorus atom and the hydrophobicity of the compounds demonstrated that these two factors play an additional effect and different role in the inhibitory activity of these compounds. Hydrolytic stability of the compounds was determined by 31P NMR monitoring of the loss of the parent molecules with D2O as a function of time. This study considers antiacetylcholinesterase activity according to the structural and the electronic aspects of compounds 1–4, according to IR, 1H, 13C and 31P NMR spectral data. 相似文献
47.
48.
Elaheh Khosrowabadi Zeinab Takalloo Khosro Khajeh 《Preparative biochemistry & biotechnology》2013,43(6):483-489
AbstractEscherichia coli is a common host that is widely used for producing recombinant proteins. However, it is a simple approach for production of heterologous proteins; the major drawbacks in using this organism include incorrect protein folding and formation of disordered aggregated proteins as inclusion bodies. Co-expression of target proteins with certain molecular chaperones is a rational approach for this problem. Aequorin is a calcium-activated photoprotein that is often prone to form insoluble inclusion bodies when overexpressed in E. coli cells resulting in low active yields. Therefore, in the present research, our main aim is to increase the soluble yield of aequorin as a model protein and minimize its inclusion body content in the bacterial cells. We have applied the chaperone-assisted protein folding strategy for enhancing the yield of properly folded protein with the assistance of artemin as an efficient molecular chaperone. The results here indicated that the content of the soluble form of aequorin was increased when it was co-expressed with artemin. Moreover, in the co-expressing cells, the bioluminescence activity was higher than the control sample. We presume that this method might be a potential tool to promote the solubility of other aggregation-prone proteins in bacterial cells. 相似文献
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Cost reduction in plant breeding and conservation programs depends largely on correctly defining the minimal sample size required for the trustworthy assessment of intra- and inter-cultivar genetic variation. White clover, an important pasture legume, was chosen for studying this aspect. In clonal plants, such as the aforementioned, an appropriate sampling scheme eliminates the redundant analysis of identical genotypes. The aim was to define an optimal sampling strategy, i.e., the minimum sample size and appropriate sampling scheme for white clover cultivars, by using AFLP data (283 loci) from three popular types. A grid-based sampling scheme, with an interplant distance of at least 40 cm, was sufficient to avoid any excess in replicates. Simulations revealed that the number of samples substantially influenced genetic diversity parameters. When using less than 15 per cultivar, the expected heterozygosity (He) and Shannon diversity index (I) were greatly underestimated, whereas with 20, more than 95% of total intra-cultivar genetic variation was covered. Based on AMOVA, a 20-cultivar sample was apparently sufficient to accurately quantify individual genetic structuring. The recommended sampling strategy facilitates the efficient characterization of diversity in white clover, for both conservation and exploitation. 相似文献