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排序方式: 共有238条查询结果,搜索用时 15 毫秒
31.
Amna T Puri SC Verma V Sharma JP Khajuria RK Musarrat J Spiteller M Qazi GN 《Canadian journal of microbiology》2006,52(3):189-196
Twigs (young and old) from Nothapodytes foetida growing in the Jammu and Mahabaleshwar regions in India were used for the isolation of 52 strains of endophytic fungi and were tested for their ability to produce the anticancer alkaloid camptothecin. One of the isolates from the inner bark tissue of the N. foetida plant growing in the Jammu region of J&K state, India, was found to produce detectable quantities of camptothecin and its derivatives when grown in a semi-synthetic liquid medium. Camptothecin was identified by physicochemical analysis and further confirmed by spectroscopic studies. No camptothecin was detected in zero time cultures or in uninoculated culture broth. The maximum yield of camptothecin was 0.575 +/- 0.031 mg/100 g of dry cell mass in 96 h in shake flasks, whereas 4.96 +/- 0.73 mg/100 g of dry mass was recorded in 48 h in a bioreactor. 相似文献
32.
Molecular Characterization of Mercury Resistant Bacteria Inhabiting Polluted Water Bodies of Different Geographical Locations in India 总被引:1,自引:0,他引:1
Mercury pollution is a major environmental problem that arises as a result of natural processes as well as from anthropogenic sources. In response to toxic mercury compounds, microbes have developed astonishing array of resistance systems to detoxify them. To address this challenge, this study was aimed in screening bacterial isolates for their tolerance against varied concentrations of phenylmercuric acetate. Mercury transformation by bacteria being sensitive to factors such as available carbon source, etc. that affect mer-mediated transformation, screened mercury tolerant bacteria were also studied for their tolerance to different antimicrobials and carbon sources, followed by identification using biochemical as well as 16S rRNA approach. Following identification, gene encoding organomercurial lyase catalyzing protonolytic cleavage of C-Hg bond of organic mercury was amplified using gene specific primers, cloned in pGEMT(?) easy vector and sequenced. Microbe-based approach using organomercurial lyase encoded by merB gene being potentially economic, provides foundation to facilitate genetic manipulation of this environmentally important enzyme to remove high concentrations of obstinate mercury using holistic, multifaceted approach for use in bioremediation through generation of transgenics or as catalyst for use in bioreactors. 相似文献
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34.
S Johri A Bhat S Sayed A Nargotra A Jain GN Qazi 《World journal of microbiology & biotechnology》2012,28(1):193-203
Thermophilic Bacillus circulans IIIB153 isolated from hot springs of North West Himalayas, India, produced an extracellular lipase, which exhibited significant
biofilm disruption property on the static biofilm disruption model with a single species of Actinomyces
viscosous. The gene encoding the lipase was cloned and overexpressed in Escherichia coli. Recombinant Bacillus circulans lipase (BCL), a monomer with molecular mass of 43 kDa also exhibited significant biofilm disruption activity. The enzyme
was optimally active at 60°C, pH 8.5 and retained >70% of its original activity after 1 h incubation at 60°C. 3D structure
of BCL developed by homology modeling showed a typical α/β hydrolase fold, a characteristic feature of lipolytic enzymes.
Comparison of thermostable BCL with mesostable lipase from Chromobacterium viscosum at the sequence and structure level showed distinct variations in the structural features, with the presence of a high content
of proline residues, aromatic amino acids and salt bridges. These features along with the presence of zinc-binding site observed
in BCL structure could have a potential role in thermal stability of the enzyme. 相似文献
35.
Kumar A Malik F Bhushan S Sethi VK Shahi AK Kaur J Taneja SC Qazi GN Singh J 《Chemico-biological interactions》2008,171(3):332-347
An essential oil from a lemon grass variety of Cymbopogon flexuosus (CFO) and its major chemical constituent sesquiterpene isointermedeol (ISO) were investigated for their ability to induce apoptosis in human leukaemia HL-60 cells because dysregulation of apoptosis is the hallmark of cancer cells. CFO and ISO inhibited cell proliferation with 48 h IC50 of approximately 30 and 20 microg/ml, respectively. Both induced concentration dependent strong and early apoptosis as measured by various end-points, e.g. annexinV binding, DNA laddering, apoptotic bodies formation and an increase in hypo diploid sub-G0 DNA content during the early 6h period of study. This could be because of early surge in ROS formation with concurrent loss of mitochondrial membrane potential observed. Both CFO and ISO activated apical death receptors TNFR1, DR4 and caspase-8 activity. Simultaneously, both increased the expression of mitochondrial cytochrome c protein with its concomitant release to cytosol leading to caspase-9 activation, suggesting thereby the involvement of both the intrinsic and extrinsic pathways of apoptosis. Further, Bax translocation, and decrease in nuclear NF-kappaB expression predict multi-target effects of the essential oil and ISO while both appeared to follow similar signaling apoptosis pathways. The easy and abundant availability of the oil combined with its suggested mechanism of cytotoxicity make CFO highly useful in the development of anti-cancer therapeutics. 相似文献
36.
Amardeep Kour Abdul S. Shawl Suriya Rehman Phalisteen Sultan Parvaiz H. Qazi Pankaj Suden Ravi K. Khajuria Vijeshwar Verma 《World journal of microbiology & biotechnology》2008,24(7):1115-1121
Podophyllotoxin, a well-known naturally occurring aryltetralin lignan occurs in few plant species that is used as a precursor
for the chemical synthesis of the anticancer drugs like etoposide, teniposide and etopophose phosphate. The availiability
of this lignan is becoming increasingly limited because of the scarce occurance of its natural sources and also because synthetic
approaches for its production are still commercially unacceptable. This paper reports first time the production of podophyllotoxin
by an endophytic fungus Fusarium oxysporum isolated from the medicinal plant Juniperus recurva. Further confirmation and quantification of podophyllotoxin was performed by HPLC, LC-MS, and LC-MS/MS. 相似文献
37.
Vijeshwar Verma Andrija Smelcerovic Sebastian Zuehlke Mir Abid Hussain Syed Mudasir Ahmad Thorsten Ziebach Ghulam Nabi Qazi Michael Spiteller 《Biochemical Systematics and Ecology》2008
The content of hypericins (hypericin and pseudohypericin), hyperforin, and flavonoids (rutin, hyperoside, quercitrin, and quercetin) and genetic profiles of eight accessions of Hypericum perforatum L., collected from different locations in India, have been determined. The secondary metabolite content was determined using a highly selective LC/MS/MS method. Pearson and Spearman's correlation coefficient were used to investigate the relationships between the secondary metabolites and a significant positive correlation was found between hypericin and pseudohypericin contents. Genetic profiling was undertaken using the random amplification of polymorphic DNA (RAPD) and single sequence repeat (SSR) methods. Among the 49 random primers used for the initial screening, only nine yielded polymorphic RAPD profiles. The SSR analysis shows that seven out of the 11 primers were polymorphic. There exists only a partial correlation between the chemical content and genetic profiling data among the accessions under study. 相似文献
38.
Qayyum Imran Zubrow Alan B. Ashraf Qazi M. Kubin Joanna Delivoria-Papadopoulos Maria Mishra Om P. 《Neurochemical research》2001,26(10):1163-1169
Previous studies have shown that hypoxia induces nitric oxide synthase-mediated generation of nitric oxide free radicals leading to peroxynitrite production. The present study tests the hypothesis that hypoxia results in NO-mediated modification of Na+, K+-ATPase in the fetal brain. Studies were conducted in guinea pig fetuses of 58-days gestation. The mothers were exposed to FiO2 of 0.07% for 1 hour. Brain tissue hypoxia in the fetus was confirmed biochemically by decreased ATP and phosphocreatine levels. P2 membrane fractions were prepared from normoxic and hypoxic fetuses and divided into untreated and treated groups. The membranes were treated with 0.5 mM peroxynitrite at pH 7.6. The Na+, K+-ATPase activity was determined at 37°C for five minutes in a medium containing 100 mM NaCl, 20 mM KCl, 6.0 mM MgCl2, 50 mM Tris HCl buffer pH 7.4, 3.0 mM ATP with or without 10 mM ouabain. Ouabain sensitive activity was referred to as Na+, K+-ATPase activity. Following peroxynitrite exposure, the activity of Na+, K+-ATPase in guinea pig brain was reduced by 36% in normoxic membranes and further 29% in hypoxic membranes. Enzyme kinetics was determined at varying concentrations of ATP (0.5 mM-2.0 mM). The results indicate that peroxynitrite treatment alters the affinity of the active site of Na+, K+-ATPase for ATP and decreases the Vmax by 35% in hypoxic membranes. When compared to untreated normoxic membranes Vmax decreases by 35.6% in treated normoxic membranes and further to 52% in treated hypoxic membranes. The data show that peroxynitrite treatment induces modification of Na+, K+-ATPase. The results demonstrate that peroxynitrite decreased activity of Na+, K+-ATPase enzyme by altering the active sites as well as the microenvironment of the enzyme. We propose that nitric oxide synthase-mediated formation of peroxynitrite during hypoxia is a potential mechanism of hypoxia-induced decrease in Na+, K+-ATPase activity. 相似文献
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40.
EmrE is a member of the small multidrug resistance (SMR) protein family in Escherichia coli. It confers resistance to a wide variety of quaternary cation compounds (QCCs) as an efflux transporter driven by the transmembrane proton motive force. We have expressed hexahistidinyl (His6) – myc epitope tagged EmrE, extracted it from membrane preparations using the detergent n-dodecyl-β-D-maltopyranoside (DDM), and purified it using nickel-affinity chromatography. The size of the EmrE protein, in DDM environment, was then examined in the presence and absence of a range of structurally different QCC ligands that varied in their chemical structure, charge and shape. We used dynamic light scattering and showed that the size and oligomeric state distributions are dependent on the type of QCC. We also followed changes in the Trp fluorescence and determined apparent dissociation constants (Kd). Overall, our in vitro analyses of epitope tagged EmrE demonstrated subtle but significant differences in the size distributions with different QCC ligands bound. 相似文献