Aim To study chemical constituents from Ampelopsis grossedentata. Methods Separation and purification were performed by using silica gel, polyamide, reverse-phase silica gel, Sephadex LH-20 column chromatographic tech...Aim To study chemical constituents from Ampelopsis grossedentata. Methods Separation and purification were performed by using silica gel, polyamide, reverse-phase silica gel, Sephadex LH-20 column chromatographic techniques and silica gel PTLC. Structures were determined by means of physicochemical properties and spectral analysis. Results Four flavonoids were separated and identified from Ampelopsis grossedentata including dihydromyricetin (1), myricetin (2), myricitrin (3), and myricetin-3-O-β-D-galactopy...展开更多
An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galact...An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galactosidase was investigated based on the cyclic voltammetric (CV) behavior of p-aminophenyl (PAP). The results obtained using the pure enzyme showed that the addition of magnesium ion facilitated the enzyme-catalytic reaction. K m at the optimal magnesium ion concentration (5 mmol/L) was 0.90 mmol/L. The substrate was also used for coliformbacteria, where β-D-galactosidase in the bacteria cells was strongly induced by isopropyl-β-D-thiogalactopyranoside (IPTG). When the E. coli cell density exceeded 1.1×10 3 mL -1, the CV response was linearly related to the number of E. coli, the detection time was about one hour. This method can be developed into a portable biosensor for rapid assay of coliform bacteria.展开更多
文摘Aim To study chemical constituents from Ampelopsis grossedentata. Methods Separation and purification were performed by using silica gel, polyamide, reverse-phase silica gel, Sephadex LH-20 column chromatographic techniques and silica gel PTLC. Structures were determined by means of physicochemical properties and spectral analysis. Results Four flavonoids were separated and identified from Ampelopsis grossedentata including dihydromyricetin (1), myricetin (2), myricitrin (3), and myricetin-3-O-β-D-galactopy...
文摘An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galactosidase was investigated based on the cyclic voltammetric (CV) behavior of p-aminophenyl (PAP). The results obtained using the pure enzyme showed that the addition of magnesium ion facilitated the enzyme-catalytic reaction. K m at the optimal magnesium ion concentration (5 mmol/L) was 0.90 mmol/L. The substrate was also used for coliformbacteria, where β-D-galactosidase in the bacteria cells was strongly induced by isopropyl-β-D-thiogalactopyranoside (IPTG). When the E. coli cell density exceeded 1.1×10 3 mL -1, the CV response was linearly related to the number of E. coli, the detection time was about one hour. This method can be developed into a portable biosensor for rapid assay of coliform bacteria.
