Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean ...Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.展开更多
Objective To construct a recombinant lactobacillus (Lb.) strain excreting the human chorionic gonadotropin beta-subunit (hCGβ) Methods The hCGβ cDNA was ligated to the signal peptide sequence of S-layer protein fr...Objective To construct a recombinant lactobacillus (Lb.) strain excreting the human chorionic gonadotropin beta-subunit (hCGβ) Methods The hCGβ cDNA was ligated to the signal peptide sequence of S-layer protein from Lb. brevis and then cloned into down-stream of lactose-inducible promoter of an integrative plasmid, pIlac. After electroporation into Lb. casei CECT5276, PCR using the genomic DNA of the recombinant lactobacillus as template was performed to confirm whether the hCGβ gene had been integrated into the genome. Radioimmunoassay (RIA) was used to determine the level of hCGβ in the supernatant and the cell lysate. Results The hCGβ was integrated into the genome of Lb. casei CECT5276. The highest concentration of hCGβ in the culture supernatant amounted to 440 mIU/mL 21 h after lactose induction. About 2/3 of the abstract Objective proteins were excreted into the supernatant. Conclusion We have obtained stable and efficient hCGβ excretion in Lb. casei, which was inducible by lactose.展开更多
基金V. ACKNOWLEDGMENTS This work was support by the National Natural Science Foundation of China （No.20577049, No.20707025, and No.20907054）, the Chinese-Slovak Scientific and Technological Cooperation Project （No.4-03）, the Excellent Youth Foundation of Anhui Province Scientific Committee （No.06045098）, the Hefei Institutes of Physical Science, Chinese Academy of Science are gratefully acknowledged, and the Slovak Research and Development Agency, projects （No.LPP-0143-06 and No.SK- CN-029-07）.
文摘Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.
文摘Objective To construct a recombinant lactobacillus (Lb.) strain excreting the human chorionic gonadotropin beta-subunit (hCGβ) Methods The hCGβ cDNA was ligated to the signal peptide sequence of S-layer protein from Lb. brevis and then cloned into down-stream of lactose-inducible promoter of an integrative plasmid, pIlac. After electroporation into Lb. casei CECT5276, PCR using the genomic DNA of the recombinant lactobacillus as template was performed to confirm whether the hCGβ gene had been integrated into the genome. Radioimmunoassay (RIA) was used to determine the level of hCGβ in the supernatant and the cell lysate. Results The hCGβ was integrated into the genome of Lb. casei CECT5276. The highest concentration of hCGβ in the culture supernatant amounted to 440 mIU/mL 21 h after lactose induction. About 2/3 of the abstract Objective proteins were excreted into the supernatant. Conclusion We have obtained stable and efficient hCGβ excretion in Lb. casei, which was inducible by lactose.
