title: alpha-Amylase determination using maltopentaose as substrate.
abstract: The rationale of choosing a NADP-coupled continuous method, with the substrate maltopentaose, as a method for the determination of alpha-amylase (EC 3.2.1.1) activity is investigated. The method presented is investigated with respect to all reaction parameters, including possible influence of protein, and shows zero order reaction kinetics after a 5-6 minute lag phase. The blank reaction from maltopentaose substrate is constant and is 13% of the upper limit of the reference interval for serum. The course of the blank reaction can be used to check that the maltopentaose is of adequate purity for use in the assay. Km for maltopentaose is 0.48 mmol/l. There is no interference from endogenous glucose when the total NADP turnover is less than 0.25 mmol/l. Data for sensitivity, linearity and long term precision over an eighteen month period are given, together with reference intervals for serum and for urine. The method is recommended for consideration as a reference method.
mesh_terms: D000681:Amylases / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D005947:Glucose; D006801:Humans; D007477:Ions; D009249:NADP; D009844:Oligosaccharides; D010179:Pancreas / Q000201:enzymology; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000032:analysis*
chemical_list: D007477:Ions; D009844:Oligosaccharides; C019193:maltopentaose; D009249:NADP; D000681:Amylases; D000516:alpha-Amylases; D005947:Glucose