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51.
S. Koul V. Verma S. Johri G. N. Qazi 《World journal of microbiology & biotechnology》1995,11(2):234-235
Erwinia herbicola (ATCC 21998), a facultative anaerobe, has two plasmids: pVQ1 and pVQ2. Curing with mitomycin C indicated that pVQ2 was cryptic but pVQ1, a 7.4-kb plasmid, bears a 4.3SacI fragment which strongly hybridized to the C-terminal region of the glucose dehydrogenase gene ofAcinetobacter calcoaceticus. A restriction map of plasmid pVQ1 is presented.The authors are with the Department of Biotechnology, Regional Research Laboratory, Canal Road, Jammu Tawi-180 001, India; 相似文献
52.
Structure and chromosomal arrangement of leghemoglobin genes in kidney bean suggest divergence in soybean leghemoglobin gene loci following tetraploidization 总被引:9,自引:0,他引:9 下载免费PDF全文
We have determined the structure of one of the leghemoglobin (Lb) genes of Phaseolus vulgaris (kidney bean) and deduced the chromosomal arrangement of leghemoglobin genes by genomic hybridizations with Lb and two other sequences, each specific to the 5' or 3' region of the soybean leghemoglobin loci. By comparing this organization with two other species of legumes, Glycine max (soybean) and G. soja (wild soybean), a phylogeny of leghemoglobin gene loci was traced. The intragenic structure of the kidney bean leghemoglobin gene shows the same intron/exon arrangement as that of soybean leghemoglobin genes and extensive sequence homologies in both coding as well as 5' and 3' non-coding regions. The presence in the kidney bean genome of four leghemoglobin genes suggests that tandem duplications of a single primordial plant globin gene had occurred to generate four leghemoglobin genes in an `Lb-locus' before Glycine and Phaseolus species diverged. Chromosome duplication by tetraploidization in Glycine generated two loci containing four genes each. A large deletion in one of the two four-gene loci in soybean resulted in the generation of the Lbc2 locus containing two leghemoglobin genes, one functional and another pseudo (LbΨ2). This pseudogene, unlike that present on the main locus, is represented by only two and a half exons and appears to be truncated. The two other truncated genes (LbT1 and LbT2) were probably generated similarly in the genome of Glycine spp. following tetraploidization before the divergence of G. max and G. soja. 相似文献
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54.
The highly purified Ca2+-pumping ATPase from human erythrocyte membranes displays two p-nitrophenylphosphatase (NPPase) activities: one of these requires calmodulin and low concentrations of Ca2+, while the other requires ATP and higher Ca2+ concentrations. The free Ca2+ concentrations required for the expression of the two NPPase activities differed very substantially. Both activities required high free Mg2+ concentrations and displayed simple hyperbolic kinetics toward p-nitrophenyl phosphate (NPP) with a Km in the range of 5-20 mM. Study of the dependence of the calmodulin-stimulated NPPase on Mg2+ and NPP indicated that the Mg-NPP complex is not the substrate of the enzyme. Under conditions optimal for ATP-requiring NPPase (1 mM free Ca2+), the Ca2+-ATPase displayed simple hyperbolic kinetics with a low Km for ATP. NPP competitively inhibited this activity, and the apparent Ki for NPP was less than 1 mM, much lower than the Km for NPP as a substrate. If NPP were inhibiting the ATPase by binding at the same site at which NPP is hydrolyzed, the apparent Ki for NPP as inhibitor would be the same as the Km for NPP as substrate. (Under these circumstances, the apparent Ki and the Km can be directly compared, since NPP was being hydrolyzed under both circumstances.) Since Ki was much lower than Km, NPP must have been inhibiting at another site; thus, these data show the existence of two types of NPP sites on the enzyme, one at which NPP is hydrolyzed and the other at which it inhibits ATP hydrolysis.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
55.
S P Verma J R Philippot B Bonnet J Sainte-Marie Y Moschetto D F Wallach 《Biochemical and biophysical research communications》1984,122(2):867-875
Low-density lipoproteins isolated between density 1.02 and 1.063 g/cm3 from normal fasting human plasma, show strong resonance Raman spectra due to the presence of beta-carotene. Three intense bands, at 1010, 1160 and 1530 cm-1, are assigned to the stretching vibrations of -C-CH3, = C-C = and -C = C- bonds, respectively, of beta-carotene. High-resolution spectra of the 1500-1600 cm-1 region reveal multiple features, suggesting the coexistence of several structural populations of beta-carotene. The modifications of lipoproteins with pH and temperature (30 degrees-42 degrees) change the resonance Raman spectra of beta-carotene. The specific binding of LDL at pH 7.0 by fibroblast cells is suppressed. Our experiments thus suggest that physical and chemical perturbations of plasma lipoproteins modify the lipid-protein interactions and thereby alter the configurational distribution of beta-carotene molecules within these particles. 相似文献
56.
All four isolates of Yersinia enterocolitica and one isolate of Y. frederiksenii from pigs were found to be enterotoxigenic. Whole-cell preparations of Y. enterocolitica isolates did not induce any change in the rabbit ligated gut test after 6 and 18 h of inoculation, but Y. frederiksenii on the other hand showed a positive gut response at 18 h. Cell-free supernatant (CFS) of all five isolates induced dilatation in the rabbit gut up to 6 h, after which Y. enterocolitica became negative, while Y. frederiksenii continued to show a reaction up to 18 h. CFS of all five isolates were also found positive with the infant mouse test. Of the five isolates of Yersinia, three gave a positive reaction for the permeability factor on rabbit skin. Yersinia enterotoxin could be concentrated by methanol extraction. It was stable at 100°C for 20 min and at 120°C for 15 min. However, its activity was lost at low (2.0) and high pH (10.0). Enterotoxic preparations of Y. enterocolitica lost part of their enterotoxic activity upon dialysis. 相似文献
57.
58.
Secretion and reabsorption of uterine luminal fluid in rats 总被引:3,自引:0,他引:3
Treatment of ovariectomized rats with oestradiol-17beta and progesterone demonstrated that oestradiol-17beta causes secretion of sodium, potassium and water into the lumen of the uterine horn and that progesterone causes reabsorption of these substances. 相似文献
59.
Detection of a transforming gene product in cells transformed by Moloney murine sarcoma virus 总被引:42,自引:0,他引:42
We identified, in cells transformed by Moloney murine sarcoma virus (M-MuSV clone 124), a protein encoded by the M-MuSV transforming gene, v-mos. An antiserum against a synthetic peptide corresponding to the C terminus of a protein predicted from the v-mos nucleotide sequence specifically recognizes a protein doublet of approximately 37,000 daltons from 35S-methionine-labeled M-MuSV 124-transformed producer cells. By peptide mapping, this protein is almost identical to the 37 kd in vitro translation product from the M-MuSV v-mos gene. Immunoprecipitates from 32P-labeled cells contain a single v-mos-specific phosphoprotein, which has at least six sites of phosphorylation containing phosphoserine. Pulse-chase experiments show that the lower band in the 35S-methionine-labeled doublet is the primary translation product, which is modified, probably by phosphorylation, to yield the upper band. A similar mos protein is immunoprecipitated from HT1-MuSV-transformed cells, but not from uninfected NIH/3T3 cells. These mos proteins are present at very low levels in transformed cell lines. Cells acutely infected with M-MuSV 124, however, transiently contain much higher levels of the mos protein. These high levels coincide with extensive cell mortality. 相似文献
60.
Pankaj Ganguly Nancy G. Fossett 《Biochemical and biophysical research communications》1980,92(2):499-504
Human platelets bind on an average of 5 × 105 molecules of lentil lectin/cell with an apparent dissociation constant of 3 × 10?7 M. The lectin binds mainly to surface glycoprotein II with an apparent molecular weight of 125,000. Lentil lectin neither caused aggregation nor did it inhibit platelet aggregation by other agents. It had no influence on the binding of thrombin to platelets or on thrombin-induced clot retraction. The hypothesis that glycoprotein II mediates platelet aggregation needs reevaluation. 相似文献