nitrophenols and 4-nitrophenyl-alpha-glucoside

A new fluorescent biosensor has been designed to screen α-glucosidase inhibitors (AGIs) sensitively by utilizing signal amplification effect of conjugated polymers. The fluorescence of cationic poly(fluorenylene phenylene) (PFP) was quenched in the presence of para-nitrophenyl-α-d-glucopyranoside and α-glucosidase, and turned on upon addition of AGIs. Thus, a new method was developed for AGIs screening based on the fluorescence turn-off/turn-on. The IC(50) values obtained for inhibitors were compared with that reported using absorption spectroscopy. All results present the new method is more sensitive and promising in screening AGIs and inhibitors of other enzymes whose hydrolysis product is 4-nitrophenol.

Topics: alpha-Glucosidases; Biosensing Techniques; Cations; Diabetes Mellitus; Fluorenes; Fluorescent Dyes; Glucosides; Humans; Hydrolysis; Inhibitory Concentration 50; Kinetics; Nitrophenols; Nitrophenylgalactosides; Polymers; Quaternary Ammonium Compounds; Spectrophotometry

The ability to utilize maltose, as determined by measurement of oxygen uptake, is used to differentiate Mycoplasma mycoides subsp. mycoides small colony (SC) and M. capricolum subsp. capripneumoniae (all strains negative) from other members of the M. mycoides cluster (M. mycoides subsp. capri, M. mycoides subsp. mycoides large colony (LC), M. capricolum subsp. capricolum; and bovine serogroup 7; 94% of strains positive). Rapid tests for maltose utilizing ability were developed, based on hydrolysis of a chromogenic alpha-glucosidase (maltase) substrate (p-nitrophenyl-alpha-D-glucopyranoside, colourless) to give a brightly coloured product (p-nitrophenol, yellow). On agar plates, colonies of maltose-utilizing strains became coloured within 40 min.

Topics: Animals; Cattle; Colony Count, Microbial; Glucosidases; Glucosides; Maltose; Mycoplasma mycoides; Nitrophenols; Oxygen Consumption

p-NP-alpha-D-Glucoside-hydrolyzing activity in the culture filtrate of Bacillus circulans KA-304, a producer of Schizophyllum commune cell-wall lytic enzyme, increased remarkably when the bacterium was grown on dextran as a carbon source. It was suggested that the increase of the activity was caused by increases of two major species, alpha-D-glucosidase I and alpha-D-glucosidase II. alpha-D-Glucosidase I, which showed a certain reactivity toward dextran, was isolated from the filtrate (MW 70 kDa, 35-fold, 10% recovery). The enzyme was stable around pH 6.5-7.5 and showed its highest activity at pH 6.5. The enzyme preparation inactivated with p-chloromerucuribenzoic acid recovered its activity by incubating with ditiothereitol. Its substrate specificity suggested that the enzyme was an exo-type enzyme with certain affinity toward alpha-1,6-glucosidic linkage.

Topics: alpha-Glucosidases; Bacillus; Chloromercuribenzoates; Chromatography, Agarose; Chromatography, Thin Layer; Dextrans; Dithiothreitol; Enzyme Inhibitors; Glucosides; Hydrolysis; Molecular Weight; Nitrophenols; p-Chloromercuribenzoic Acid; Schizophyllum; Substrate Specificity; Sulfhydryl Reagents