Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small intestine cell nuclei incubated in sucrose media released large fractions of DNA into the culture medium. This effect was partially or completely suppressed when incubation was carried out in the presence of a protease inhibitor, 10 to 30 mM NaHSO3. The DNA released in sucrose media containing NaHSO3 was precipitated as a DNA-protein complex by increasing the bivalent ion concentration to 10 mM Ca2+ or 20 mM Mg2+. Most of the released DNA was not precipitated by Ca2+ or Mg2+ when incubation was performed without NaHSO3. As determined by viscosity measurements the mean molecular weight of the DNA released in the absence of NaHSO3 was from 3.5-8.0 x 10(5) and increased to about 11 x 10(5) (corresponding to 8 nucleosomes) when the incubation mixture contained NaHSO3. End group analysis indicated that the DNA segments were terminated by 3'-OH groups. It is suggested that fragmentation of DNA in chromatin was produced by a endogenous alkaline endonuclease activity which was present in the fraction of released DNA. The data support the view that the third-order repeat structure of chromatin consists of subunits containing 8 nucleosomes.
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PMID:High order packing of DNA as revealed by autodigestion of chromatin in small intestine cell nuclei. 626 19

The fed operon gene clusters with each size of 5.6kb, encoding the F18ab or F18ac fimbriae, was amplified respectively by high fidelity PCR using the genomic DNA templates from F18 fimbriae E. coli strains 107/86 or 2134P. The PCR products with the restriction enzyme sites at each end were digested and then cloned into the vector pET-22b (+), the recombinant plamids with the inserts of both type of fed gene clusters were constructed and screened, further confirmed by the means of combination with restriction endonuclease analysis and sequencing. The both types of fimbriae F18ab and F18ac were expressed efficiently in the E. coli BL21 (DE3) after proper concentration of IPTG induction. Expressed fimbriae were revealed and confirmed by transmissible electromicroscope observation. The both fimbriae F18ab and F18ac were isolated and purified from the recombinant E. coli, and only a single major band of protein with size of approximately 15kDa was visualized in Coomassie blue-stained gels after SDS-PAGE. The rabbits sera with high titer of anti-F18 fimbriae were detected after being immunized with the purified F18ab or F18ac fimbriae. The results of combination of agglutination assay with Western blotting showed that the sera directed against both fimbriae F18ab and F18ac reacted positively with the F18 fimbriae from both wild E. coli 107/86 and 2134P. Small intestine epithelial cells with F18 fimbriae receptors, which were from post-weaning piglets with the genotypes of FUT1 gene both M307(GG) and M307(AG), were prepared and tested for the adherence of E. coli expressing F18 fimbriae under the microscopic examination. Adhesion and adhesion inhibition test showed both of the recombinant E. coli expressing F18ab or F18ac fimbriae respectively could adhere to the jejunal epithelial cells in vitro as E. coli 107/86 and 2134p did. The both of anti-sera directed against fimbriae F18ab or F18ac respectively can efficiently inhibit the fimbriae-mediated post-weaning piglet jejunal epithelial cells adherence to both the recombinant E. coli (expressing F18ab or F18ac fimbriae) and wild type E. coli (107/86 and 2134P).
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PMID:[Cloning and expression of F18 fimbrial operon gene clusters from enterotoxigenic Escherichia coli and their bioactivity]. 1806 50