Papers by Author: Shi Yong Gao

Abstract: To explore how to calculate the effect of solanine on the Michaelis constant and the maximum reaction rate of NAT using the double reciprocal method. High performance liquid chromatography (HPLCP) was used, with 2-AF as substrate and its concentration as substrate concentration, and the rate at which 2-AF is acetylated into 2-AAF in intact HepG₂ cells or in the cytoplasm of HepG₂ cells as the reaction rate. The double reciprocal plot was made, with 1/S (reciprocal of the concentration of the substrate 2-AF) plotted against 1/V (reciprocal of the reaction rate), to yield a regression equation for calculating Km and Vmax. Studies on enzymetic kinetics have shown that, with intact HepG₂ cells, the Km and Vmax for the negative control are 2.37×10^-3±8.37×10^-5 mM and 9.16×10^-4±7.54×10^-5nmol/106 cells, respectively, and that the Km and Vmax for the solanine group are 2.22×10^-3±9.05×10^-5mM and 5.14×10^-4±3.72×10^-5nmol/106 cells, respectively. For the cytoplasm of HepG₂ cells, the Km and Vmax for the negative control are 8.95×10^-3±2.61×10^-4 mM and 2.55×10^-6±1.92×10^-8nmol/min·mg protein, respectively, and the Km and Vmax of the solanine group are 9.48×10^-3±3.63×10^-4mM and 2.43×10^-6±1.32×10-8 nmol/min·mg protein, respectively. Statistical analysis showed that, for both intact HepG₂ cells and cytoplasm of HepG₂ cells, Km does not differ significantly between the negative control and the solanine groups, but Vmax does differ significantly for these groups (p<0.001 for the intact cells, p<0.05 for the cytoplasm). Solanine is a non-competitive inhibitor for the 2-AF substrate of NAT, and the double reciprocal method is a convenient and accurate method for calculating the constants of NAT kinetics.

Abstract: To investigate the mechanism on Capparis spionosa L polysaccharide(CSPS) inducing apoptosis in HepG2 human hepatoma cell. MTT was ddopted to determine if CSPS had cytotoxic effect on HepG2. Morphology of HepG2 changed with dosages of CSPS was detected by laser confocal scanning microscope. Flow cytometry(FCM) was used to detect the apoptosis by PI labeling method. Calcium, mitochondrial membrane potential, Bcl-2/Bax of HepG2 cells were detected by laser confocal scanning microscope. The result of MTT showed that CSPS could inhibit the growth of HepG2 significantly. HepG2 cells were shrinkage, fragmentation, appearance of apoptotic bodies by laser confocal scanning microscope. HepG2 cell apoptosis rate was increased gradually with dosage by FCM. Calcium concentration, mitochondrial membrane potential, Bcl-2 protein of HepG2 were decreased, Bax protein content of HepG2 was increased by laser confocal scanning microscope. CSPS induced HepG2 apoptosis by controlling Bax/Bcl-2 in Ca²⁺ path.