[Microchemical investigation of alpha D-glucosidases using 4-methylumnelliferyl- and 2-naphthyl-alpha-d-glucoside (author's transl)].

In crude homogenates prepared from freeze-dried cryostate sections of various rat organs the Km and Vmax of acid and neutral alpha-glucosidase as well as the effect of the pH, substrate and enzyme concentration and the incubation time on the activity were determined fluorometrically with 4-methylumbelliferyl- and 2-naphthyl alpha-d-glucoside as substrates. On the basis of the biochemical data 2 assays were developed for the microchemical measurement of both alpha-glucosidases in groups of epithelial cells isolated from freeze dried cryostate sections of the epididymis, jejunum, ilium, liver and kidney of suckling and adult rats. The rate of hydrolysis of 2-naphthyl and 4-methylumbelliferyl alpha-d-glucoside differs moderately. However, due to the higher sensitivity of 4-methylumbelliferone the methylumbelliferyl derivative is preferable especially for the evaluation of alpha-d-glucosidases in cells with low enzyme activity.