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1.
2.
Paul J. Chuba Myron A. Leon Amit Banerjee Sunil Palchaudhuri 《Molecular & general genetics : MGG》1989,216(2-3):287-292
Summary
Escherichia coli K12 cells carrying a cloned 1.4 kb HindIII fragment from plasmid ColV2-K94, showed increased survival in guinea pig serum. The recombinant plasmid also conferred group II surface exclusion, i.e. the cells were reduced in recipient ability towards the incoming plasmid R538drd in conjugation experiments. Southern blotting suggested homology with bacteriophage lambda DNA and to the insertion element IS2. Determination of the DNA sequence of the fragment demonstrated the presence of a truncated IS2 (165 bp), separated by 250 bp from a 900 bp stretch of homology with lambda DNA, beginning within the Rz gene and continuing in the rightward direction on the lambda map. A 97 amino acid open reading frame (ORF) adjacent to Rz and on the opposite strand, remained intact in iss, with several amino acid changes. The ORF in iss is preceded by sequences resembling prokaryotic ribosome binding sites and promoters. 相似文献
3.
Rakesh M. Vohra Uttam C. Banerjee Sunil Das Syamalima Dube 《Biotechnology letters》1989,11(12):851-854
Summary A highly active extracellular rifamycin oxidase was isolated fromCurvularia lunata var.aeri. The enzyme has a pH optimum of 6.5 and temperature optimum of 50°C. 相似文献
4.
Vibrational analysis of the structure of gramicidin A. I. Normal mode analysis. 总被引:1,自引:1,他引:0
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Normal mode frequencies have been calculated for single-stranded beta 4.4 and beta 6.3 and for double-stranded increases decreases beta 5.6, increases decreases beta 7.2, increases increases beta 5.6, and increases increases beta 7.2 helices that are possible models for the structure of gramicidin A. The force field used in the calculations is one that reproduces the frequencies of model polypeptide chain structures to about +/- 5 cm-1, and is therefore expected to provide meaningful distinctions between these conformations. The calculations predict significant differences in the infrared and Raman spectra of these beta-helices, suggesting that they should be identifiable from their spectra (which is shown in the following paper to be the case). The most sensitive region is that of the amide I frequencies, where the predicted patterns of intense infrared mode, infrared splittings, and intense Raman mode provide a characteristic identification of each of the above structures. 相似文献
5.
H. O. Jauregui P. N. McMillan J. Driscoll S. Naik 《In vitro cellular & developmental biology. Plant》1986,22(1):13-22
Summary Long-term monolayer cultures of adult rat hepatocytes were tested for their ability to glucuronize phenol red and to maintain
initial levels of cell proteins, glucose consumption, and lactic acid production. Lactate dehydrogenase leakage served as
an index of culture status because a high value indicates cell death. Three tissue culture (TC) media formulations were the
main variables introduced to determine ideal conditions for cell survival in vitro. Investigations of long-term cultures were
preceded by studies of hepatocyte attachment to polystyrene surfaces. This attachment was influenced by the amount of substrate
deposited and the number of cells seeded, but not by the uniformity of the substrate coating. A statistical analysis of our
data revealed that in the absence of fetal bovine serum (FBS), air dried collagen (ADC) and Biomatrix (BMX) were superior
to saline precipitated collagen and fibronectin as attachment substrates. In the presence of 10% FBS, all of the substrates
performed equally.
Chee's Medium (CEM) proved to be the best for preserving cell proteins over a time course of 28 d and Williams' E medium also
performed adequately up to 14 d. The glucuronization of phenol red was at 50% of initial values at Day 7 in CEM-ADC hepatocytes
in contrast to 30% for cells in Williams' E medium and 5% for cells grown in Waymouth's. At 14 d glucuronization was still
present at 40% of original values in CEM-ADC cells but had ceased in the other two media. When BMX was used, none of the TC
media supported glucuronization levels comparable to ADC cells.
This research was supported in part by grant 1R01-AM-26520 from the National Institute of Arthritis, Diabetes and Digestive
Kidney Diseases, NIH, Bethesda, Maryland. 相似文献
6.
S Naik J E Oates A Dell G W Taylor P M Dey J B Pridham 《Biochemical and biophysical research communications》1985,132(1):1-7
A fast atom bombardment mass spectrometric protocol has been developed to determine the type of oligosaccharide chain present in glycoproteins. The procedure is based on acetolysis of the intact glycoconjugate, extraction of the peracetylated carbohydrate fragments and analysis by fast atom bombardment mass spectrometry. The molecular ions present in the FAB spectra uniquely define the composition of the oligosaccharides with respect to hexose, aminohexose and sialic acid content. High mannose oligosaccharides yield a series of peracetylated hexose oligomers whereas complex-type oligosaccharides afford a series of N-acetyl-lactosamine containing species. Fucosylation is usually not detected but sialylated oligosaccharides are readily identified and the type of sialic acid is also defined. The method has been tested on three glycoproteins of known structure - fetuin, ribonuclease B and erythrocyte Band 3 - and on a glycoprotein of unknown structure - alpha-galactosidase I, an enzyme lectin from Vicia faba. The latter is shown to contain high mannose carbohydrate chains. 相似文献
7.
A restriction enzyme map of the IncFI plasmid ColV2-K94 was generated using EcoRI, BamHI, HindIII, and XhoI; the genetic features of this element were then mapped from previous heteroduplex studies. 相似文献
8.
Sunil Palchaudhuri Ranajit Kumar Dipak Sen Ruma Pal Sajal Ghosh Banwarilal Sarkar Sujit K. Bhattacharya Sudhir C. Pal 《FEMS microbiology letters》1985,30(1-2):187-191
Abstract Multiple antibiotic-resistant Shigella dysenteriae type 1 isolates from a recent epidemic in West Bengal (India) showed identical plasmid patterns. All isolates were resistant to ampicillin (Am), chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm) and trimethoprim (Tp) and contained 6 plasmids, ranging from 2.5–120 kb. The Am resistance determinant was located on the 120 kb plasmid. This plasmid was unstable when the S. dysenteriae strains were grown above 37°C. The Bangladesh strains of S. dysenteriae type 1 showed identical plasmid patterns, except that many isolates were Am-sensitive and lacked the 120 kb plasmid. In strains from both Bangladesh and West Bengal, predominantly group-B plasmids conferred resistance to Cm and Tc. Comparisons of Eco R1 fragments generated from the total plasmid DNA content of each strain support the view that the plasmids present in the S. dysenteriae type 1 strains isolated from all recent epidemics in India and Bangladesh were identical. 相似文献
9.
10.
M. S. Naik D. J. D. Nicholas 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,72(6):735-736
Summary Leaves of young seedlings of a number of tall cultivars of wheat, lacking the dwarfing Rht genes, readily responded to a brief 2 min exposure to CO, as assessed by in vivo aerobic assay of nitrate reductase. This test depends on the inhibition of cytochrome c oxidase by CO, which in turn renders cytosolic NADH available for the reduction of nitrate to nitrite in vivo. Semi-dwarf cultivars of wheat (Rht present) did not respond to CO in this way. Since CO forms a complex only with reduced cytochrome a3, the results indicate differences in the redox state of cytochrome a3, during in situ respiration of leaves from tall and semi-dwarf plants which are likely to be under genetic control. 相似文献