Studies on acid protease fractions and gastric mucosal atrophy. 1. A modified simple method for separate determination of alkali labile pepsin in gastric juice by alkali treatment or by using a synthetic substrate.

A modified simple method applicable for clinical purpose for separate determination of "pepsin" and "gastricsin" by alkali treatment is reported. The method includes dialysis against 0.1 M acetate buffer, pH 5.3 and incubation in an equal volume of 0.1 M phosphate buffer, pH 7.8 to give a final pH of 7.25, at 25 degrees C for 20 minutes, and has a good reproducibility. N-acetyl-L-phenylalanyl-L-diiodotyrosine (APDT) hyprolysing activity and alkali labile pepsin activity are correlated very well. Nevertheless the former cannot completely be destroyed by the treatment.