Characteristic of Fura-2-Ca^(2+)interaction was studied based on the fluorescence technique.The apparent dissociation constants(K_d)of the Fura-2-Ca^(2+)complex were determined at different temperature.The effect of cefotaxime(CEFA)on intracellular Ca^(2+)concentration([Ca^(2+)]_i)was discussed by using a ratiometric fluorescence dye Fura-2 as a probe.The basal[Ca^(2+)]_i in resting humanperipheral lymphocytes was 100 7 nmol/L but after treatment with cefotaxime,the changes of[Ca^(2+)]_i were observed in differentconditions.In the concentration range of 1-30 μmol/L of cefotaxime[Ca^(2+)]_i increased,as a result of releasing intracellular Ca2+stores.Higher concentration of cefotaxime(50-500 μmol/L)stimulated to decrease of[Ca^(2+)]_i.
Dan Dan WangHai Yan WangYe Hong ZhouChun Gui ZhaoChuan DongShao Min Shuang
The effect of penicillin on the human peripheral lymphocytes was studied by steady fluorescent technique and ratiometric fluorescence dye, Fura-2. The change of the free calcium concentration in cytosol was examined under different conditions. A characterization of Fura-2-Ca interaction in an isotonic saline solution showed that Ca2+ formed a 1*1 Fura-2-Ca complex with the apparent dissociation constant 1.81×10-7 mol/L. The mechanism, by which penicillin induced the decrease of [Ca2+]i , was discussed in detail. The low dose of penicillin might modify the lymphocytes’ immunology response by interfering the increase in the intracellular free calcium concentration.
Hai Yan WANGDan Dan WANGChun Gui ZHAOYe Hong ZHOUShao Min SHUANGChuan DONG
The interactions between L-tryptophan(L-Trp) and water-soluble p-sulfonatocalix[4]- arene (SCX4) were investigated by spectrofluorometry. The effect of pH was discussed. The interaction process was estimated from the thermodynamic viewpoint. The SCX4 was found to be able to adjust its conformation to fit the size of L-Trp, and the benzene of L-Trp penetrated into the hydrophobic cavity of SCX4. Meanwhile, the binding mechanism was further elucidated by 1H NMR and molecular mechanics calculations.
Wen Ye LIYing Li WEIWen Ting ANShao Min SHUANGMan Shing WONG
