Determination of trypsin by its accelerating effect on the onset of trypsinogen activation

A method for the determination of trypsin activity is described, based on the kinetics of trypsinogen to trypsin conversion. The time of onset of the autocatalytic conversion, followed in vitro, was found to depend on the amount of exogenous trypsin added. The time for half-maximal trypsinogen conversion was proportionally shortened from 240 to 20 min within the range of 0–1 μg trypsin added to an incubation system containing a large excess of trypsinogen. Optimum conditions for the assay, in terms of temperature dependence and trypsinogen concentration, were determined. The method can be used for the measurement of trypsin in purified preparations and in biological specimens devoid of other activators of trypsinogen. The amount of performed trypsin in pancreatic extracts from rats in some pathological conditions may also be estimated.