[Denaturation of the alpha-amylase of Bacillus subtilis in an acid medium].

By fractionation of purine compounds (sorbtion on the cation exchange resin KU-2 (H+), extraction, precipitation of purine compounds as Ag-complexes) a "purine fraction" of the culture liquid epiphytic bacteria No. 703 isolated from barley overground organs was obtained. The presence of isopentenyl cytokinins was demonstrated by quality reactions of the purine fraction with aromatic amines and phenols as well as by the values of Rf and UV spectrum of individual compounds examined by paper chromatography of the purine fraction.