Effects of proteins and polynucleotides on the activity of various hydrolases

The effect of various macromolecules on the activity of several hydrolases was studied. Dilution of partially purified acid beta-galactosidase from ileal mucosa of suckling rats resulted in a decrease of specific activity. The relationship between specific activity and dilution of the enzyme suggests a dissociation of the enzyme. This could be prevented by addition of several proteins tested. However, addition of DNA to the assay mixture for acid beta-galactosidase caused an inhibition. This inhibition could be prevented by addition of proteins. Other polynucleotides and tRNA also exert an inhibitory effect that is prevented by albumin, but nucleotides have no effect. This inhibition occurs maximally at a low pH (3.0-4.0); no inhibition is observed at pH5.5. A similar pH-dependent inhibition by DNA was also found with various other acid hydrolases.