[Changes in the activity and tertiary structure of beta-amylase from wheat seeds under the effect of salts]

Changes are observed of 1-anylinonaphtalene-8-sulphonate probe fluorescence intensity, connected with beta-amylase in the presence of Ca(NO3)2, Mg(NO3)2, KNO3, NH4NO3 and (NH4)2SO4 at a concentration range within 10(-4)--1 M. Considerable decrease of the fluorescence intensity was observed under the addition of all the salts mentioned at concentration of 10(-3)--10(-4) M. A quantum yield increase of probe fluorescence was noted for Mg(NO3)2 (10(-4) M). High concentrations of Ca(NO3)2 and Mg(NO3)2 (0.25--1 M) also resulted in a sharp increase of the fluorescence intensity. Changes of beta-amylase activity took place simultaneously. The changes of the enzyme activity are suggested to be due to changes in the conformation of the enzyme protein under the effect of salts.