Action pattern of serum amylase using p-nitrophenyl-maltoheptaoside as substrate.

Selected serum samples with different isoamylase patterns, as revealed by agarose gel electrophoresis, were analysed by the Phadebas amylase test, and by using p-nitrophenyl-maltoheptaoside as the substrate. The products with the latter substrate were examined by high performance liquid chromatography (HPLC). For some samples, different catalytic activities were registered by the two amylase methods. In these cases, electrophoresis showed a double pancreatic band associated with increased pancreatic amylase catalytic activity, or an abnormal, broad salivary band associated with increased salivary enzyme catalytic activity. The stoichiometric factors for most of these samples, calculated from the amount of p-nitrophenol detected after HPLC, differed from the mean values.