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71.
Sarma AV Ramana Rao MH Sarma JA Nagaraj R Dutta AS Kunwar AC 《Journal of biochemical and biophysical methods》2002,51(1):27-45
Several cyclic analogues of renin inhibitors, based on Glu-D-Phe-Lys motif have been investigated by NMR spectroscopy and molecular dynamics calculations (MD). The 15 membered macrocycle, resulting from Glu and Lys side-chain cyclization, exhibits conformational preference. The structural evidence from NMR shows the presence of hydrogen bond between Lys NH and Glu side-chain carbonyl, resulting in a 10 membered pseudo beta-turn-like structure. The structure of the cyclic moiety is similar in all the peptides, which takes at least two conformations around Calpha-Cbeta in Glu side chain. The restrained MD calculations further support such observations and show that the macrocycle is fairly rigid, with two conformations about the Glu Calpha-Cbeta bond. The linear peptide appendages, which are essential for activity in cyclic peptides, show an extended structure in the beta-region of Ramchandran plot. These calculations also demonstrate that for the most active peptide, two major conformers each exist about the Calpha-CO bond of the Lys, D-Trp and Leu residues. In this peptide, the cyclic moiety presents a negatively charged surface formed due to the carbonyl oxygens, which are thus available to form hydrogen bonds with the receptor. The linear fragment presents further binding sites with a surface which has the hydrophobic side chains of D-Trp, Leu and D-Met on one side and carbonyls on the other side. 相似文献
72.
Evaluation of genetic diversity among Pseudomonas citronellolis strains isolated from oily sludge-contaminated sites 总被引:2,自引:0,他引:2
Bhattacharya D Sarma PM Krishnan S Mishra S Lal B 《Applied and environmental microbiology》2003,69(3):1435-1441
The diversity among a set of bacterial strains that have the capacity to degrade total petroleum hydrocarbons (TPH) in soil contaminated with oily sludge (hazardous hydrocarbon waste from oil refineries) was determined. TPH is composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compound, and asphaltene fractions of crude oil. The 150 bacterial isolates which could degrade TPH were isolated from soil samples obtained from diverse geoclimatic regions of India. All the isolates were biochemically characterized and identified with a Biolog microbial identification system and by 16S rDNA sequencing. Pseudomonas citronellolis predominated among the 150 isolates obtained from six different geographically diverse samplings. Of the isolates, 29 strains of P. citronellolis were selected for evaluating their genetic diversity. This was performed by molecular typing with repetitive sequence (Rep)-based PCR with primer sets ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and PCR-based ribotyping. Strain-specific and unique genotypic fingerprints were distinguished by these molecular typing strategies. The 29 strains of P. citronellolis were separated into 12 distinguishable genotypic groups by Rep-PCR and into seven genomic patterns by PCR-based ribotyping. The genetic diversity of the strains was related to the different geoclimatic isolation sites, type of oily sludge, and age of contamination of the sites. These results indicate that a combination of Rep-PCR fingerprinting and PCR-based ribotyping can be used as a high-resolution genomic fingerprinting method for elucidating intraspecies diversity among strains of P. citronellolis. 相似文献
73.
Chatterjee DK Sarma P Jani RH Klesel N Isert D 《Indian journal of experimental biology》2000,38(7):681-686
Balhimycin and desglucobalhimycin are glycopeptide antibiotics isolated from an Amycolatopsis spp during the search for novel antibacterials against MRSA from the natural product screening at the Research Centre of formerly Hoechst India Ltd. in Bombay, India. Both compounds show excellent in vitro activity against methicillin sensitive and resistant Staphylococcus aureus (MSSA, MRSA). Both compounds were also found to be active against a number of MRSA strain in the animal studies. The activities were comparable to that of the reference glycopeptides vancomycin and teicoplanin used in these studies. Teicoplanin displayed better in vivo efficacy against S. epidermidis 4929H and Streptococcus pyogenes A77 than either vancomycin or desgluco-balhimycin in the present study. Preliminary studies on pharmacokinetic and acute toxicity were done to get some idea at the early stage of the investigation about the promise of the compounds for development. 相似文献
74.
The addition of a nitrogen (nitrate) and carbon sources (acetate, citrate and fructose) and phosphate deficiency (nitrate
medium deficient in phosphate) under unaerated conditions induced akinete differentiation inAnabœna torulosa. Aerated cultures of this organism in these nutrients did not differentiate akinetes. Oxygen evolution by aerated cultures
was higher when compared to unaerated cultures, which concurred with high chlorophyll content of aerated cultures. Nitrate
nitrogen supported high phycocyanin content in unaerated cultures, phycocyanin and allophycocyanin contents were low under
aerated conditions. The contents of phycocyanin, allophycocyanin, phycoerythrin and carotenoids gradually decreased at the
mature akinete phase. Under aerated conditions, chlorophyll content rose and the content of all the pigments increased with
the growth rate of the organism. 相似文献
75.
Three olean-12-ene type triterpenoid saponins, named TR-saponins A, B and C, were isolated as methyl esters from tea roots (Camellia sinesis var. assamica) after treatment with diazomethane. Their structures were established as the methyl esters of 3-O-alpha-L-arabinopyranosyl (1-->3)-beta-D-glucuronopyranosyl-21, 22-di-O-angeloyl-R1-barrigenol-23-oic acid, 3-O-alpha-L-arabinopyranosyl (1-->3)-beta-D-glucuronopyranosyl-21-O-angeloyl-22-O-2-me thylbutanoyl-R1- barrigenol-23-oic acid and 3-O-alpha-L-arabinopyranosyl (1-->3)-beta-D-glucuronopyranosyl-16 alpha-O-acetyl-21-O-angeloyl-22-O-2-methylbutanoyl-R1-bar rigenol-23-oic acid, by extensive 1D and 2D-NMR as well as FABMS and HR-MS analyses. 相似文献
76.
Phylogenetic Relationships of Acanthocephala Based on Analysis of 18S Ribosomal RNA Gene Sequences 总被引:3,自引:0,他引:3
García-Varela M Pérez-Ponce de León G de la Torre P Cummings MP Sarma SS Laclette JP 《Journal of molecular evolution》2000,50(6):532-540
Acanthocephala (thorny-headed worms) is a phylum of endoparasites of vertebrates and arthropods, included among the most
phylogenetically basal tripoblastic pseudocoelomates. The phylum is divided into three classes: Archiacanthocephala, Palaeacanthocephala,
and Eoacanthocephala. These classes are distinguished by morphological characters such as location of lacunar canals, persistence
of ligament sacs in females, number and type of cement glands in males, number and size of proboscis hooks, host taxonomy,
and ecology. To understand better the phylogenetic relationships within Acanthocephala, and between Acanthocephala and Rotifera,
we sequenced the nearly complete 18S rRNA genes of nine species from the three classes of Acanthocephala and four species
of Rotifera from the classes Bdelloidea and Monogononta. Phylogenetic relationships were inferred by maximum-likelihood analyses
of these new sequences and others previously determined. The analyses showed that Acanthocephala is the sister group to a
clade including Eoacanthocephala and Palaeacanthocephala. Archiacanthocephala exhibited a slower rate of evolution at the
nucleotide level, as evidenced by shorter branch lengths for the group. We found statistically significant support for the
monophyly of Rotifera, represented in our analysis by species from the clade Eurotatoria, which includes the classes Bdelloidea
and Monogononta. Eurotatoria also appears as the sister group to Acanthocephala.
Received: 12 October 1999 / Accepted: 8 February 2000 相似文献
77.
The differentiation of akinetes inScytonema fritschii occurred adjacent to the newly developed heterocysts in late exponential phase. The filaments exhibited cell division leading
to the formation of heterocysts, interspersed by the potential akinetes which could be identified by the accumulation of a
large number of granules. Upon maturity, the akinetes acquired thick envelopes and were seen in elongated series interrupted
by dead necridia which resulted from crumpling of the newly developed heterocysts. The formation of akinetes was accompanied
by a change in color of cultures from blue-green to brown. Of the inorganic nitrogen sources tested, ammonium nitrate supported
the formation of maximum percentage of akinetes. The incorporation of 7-azatryptophan and rifampicin in nitrate-free and nitrogen
sources resulted in the production of heterocysts at a very high frequency in the late-exponential phase coinciding with akinete
formation but the frequency of the latter was reduced. The activity of nitrogenase, nitrate reductase and glutamate-ammonia
ligase was absent in mature akinetes. The absorption spectra of chlorophylla and phycobiliproteins revealed the presence of negligible amounts of the former white the latter were absent. The dry mass
steadily increased during akinete differentiation with a concomitant decrease in C/N ratios. 相似文献
78.
Comparative mapping of the wheat chromosome 5A Vrn-A1 region with rice and its relationship to QTL for flowering time 总被引:3,自引:0,他引:3
R. N. Sarma B. S. Gill T. Sasaki G. Galiba J. Sutka D. A. Laurie J. W. Snape 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):103-109
The vernalization gene Vrn-A1 on chromosome 5A is the predominant gene determining the spring/winter habit difference in bread wheat. Vrn-A1 was physically mapped using a set of deletion lines which located it to the region of chromosome 5A flanked by deletion breakpoints
0.68 and 0.78. This interval was shown to be homoeologous to a region of rice chromosome 3 that contains the flowering-time
QTL Hd-6, previously mapped in a Nipponbare×Kasalath cross, and FLTQ1, a novel QTL identified by analysis of 78 F3 families derived from a cross of ‘IR20’ב63–83’. Possible relationships between Vrn-A1 and rice QTL are discussed. Analysis of the chromosome 5A deletion lines showed evidence for a second, more proximal flowering-time
effect located between deletion breakpoints 0.56 and 0.64. The proximal part of chromosome 5A is homoeologous to rice chromosome
9, on which two QTL were detected in the ‘IR20ב63–83’ cross. The possible relationship between these effects is also discussed.
Received: 23 December 1997 / Accepted: 12 January 1998 相似文献
79.
Plant regeneration and multiplication of the emergent wetland monocot Juncus accuminatus 总被引:2,自引:0,他引:2
A reliable callus regeneration and shoot multiplication system for wetland monocot Juncus accuminatus has been established. Callus was induced from 6-day-old seedlings on Murashige and Skoog medium supplemented with 5 mg/l
picloram. The callus differentiated into shoots upon transfer to 5 mg/l benzyladenine (BA)-supplemented medium. Effects of
medium pH (3.8–7.8) and source of callus (grown in the dark or continuous light) on regeneration were determined. Both parameters
significantly influenced regeneration. Regenerated shoots were multiplied by subculturing shoots onto 5 mg/l BA medium at
4-week intervals. The regenerated shoots were rooted on 0.1 mg/l naphthaleneacetic-acid-supplemented medium. The rooted plants
were transferred to pots containing a commercial potting mix and established in the greenhouse. Plants covered with plastic
grew faster and flowered earlier than uncovered plants. All plants set viable seeds.
Received: 21 July 1997 / Revision received: 23 December 1997 / Accepted: 19 January 1998 相似文献
80.
Ahmed Kamal D. Dastagiri M. Janaki Ramaiah E. Vijaya Bharathi J. Surendranadha Reddy G. Balakishan Pranjal Sarma S.N.C.V.L. Pushpavalli Manika Pal-Bhadra Aarti Juvekar Subrata Sen Surekha Zingde 《Bioorganic & medicinal chemistry》2010,18(18):6666-6677
A series of 2,5-diaryloxadiazole linked pyrrolo[2,1-c][1,4]benzodiazepine conjugates have been prepared and evaluated for their anticancer activity. These conjugates have shown promising activity with GI50 values ranging from <0.1 to 0.29 μΜ. It is observed that some of these conjugates particularly 4a, 4d, 4i and 4l exhibit significant anticancer activity. Some detailed biological assays relating to the cell cycle aspects associated to Bax and caspases have been examined with a view to understand the mechanism of action of these conjugates. 相似文献