Abstract:The E7 gene of human papillomavirus type 16 was expressed in Escherichia coli with a recombinant plasmid prepared previously in our laboratory.The E7 fusion protein produced and purified by gel electrophoresis was used as antigen to immunize rabbits for preparing anti-E7 protein antisera.The antisera were used to stain the tissue sections often cases of uterine cervical cancer with an immunohistochemical technique(colloidal gold labeled stain).The E7 antigen was seen in the cells of 6 cases of cervical carcinoma as black granules under light microscope. The E7 protein was found in the nucleus of positive cells, mainly on the nuclear membrane, arranged in a circle. Only a few silver stained granules were seen in the cytoplasm. We believe that the intracellular distribution of the E7 protein indicates that there is high expression of the E7 gene in the HPV infected cells of the cervical cancer; and the fact that E7 antigen is a nuclear protein suggests that E7 gene is an oncogene of HPV 16.

Abstract:The UV absorption and resonance Raman spectra were recorded from the trimer allo-phycocyanin and pH-induced monomer allophycocyanin from blue-green alga Phormidium Iuridum.Monomerization mostly results in the disappearance of characteristic absorption peak 650nm,and in the changes in relative intensities and positions of Raman bands of phycocyanobilin chromophores.As a result,in the monomeric allophycocyanin,the chromophores adopt cyclohelical conformations,which close to these of free chromophores in vitro; and in the trimeric allophycocyanin, fully extended conformations of the chromophores can be marked by the main Raman peak around 1645 cm^-1, the behaviour of which is in Rood agreement with the A_vis/A_uv, absorption ratio.

Abstract:The ion channel formation of fragment B of tetanus toxin in an artificial lipid bilayer was described.Fragment B with a molecular weight of 48000 was purified by fast protein liquid chromatography.The channel activities were recorded from an asolectin bilayer memberane by patch clamp technique.It rarely formed ion channels at neutral or acidic pHs.In contrast,with pH gradient the channel activities of fragment B were easily recorded.By analysis of single channels formed by fragment B,the conductance of the channel was 2.3pS. At different holding potentials (-100-+150mV) the channels gave same conductance, it indicated that “the fragment B channel” passed K ion in both directions. The opening-time of the channel was maintained at 20-40 and 100-120ms, and the closing-time of it was main at 20ms. These results indicated that the channel of fragment B was rapidly flickering between the states of opening and closing.

Abstract:The method of PEG/phosphate salt two phase extraction as the first step of purification to prepare duck serum choline esterase was first used in this paper.The procedure was not only simple,rapid but also high in the activity recovery of the choline esterase.The purified choline esterase with specific activity 279.9 U/mg was followed by DEAE-sephadex A50 and sephadex G200 chromatography.The choline esterase was purified 1018-fold and the activity recovery of 43.4 per cent was obtained.Studies on the properties of the choline esterase showed that it was a kind of glycoproteins and acid hydrolases. The isoelectric point of 4.2 and the optimum pH of 7.5 were obtained. The K_m of 9.8×10^-5mol/L with butyryl-thiocholine iodide was determined. SDS and polyacrylamide gel electrophoresis showed that the choline esterase existed in the different polymers composed of the same subunit. The molecular weight of subunit was 78000, and the subunit had the activity of the whole choline esterase.