Effect of cerium on activity of alpha-amylase from porcine pancreas

The activity of a-amylase from porcine pancreas was enhanced under the treatment by Ce3+ of low concentration (0.5 similar to 10 mumol . L-1), but was inhibited by Ce3+ of high concentration ( > 10 mumol . L (-1)). Ce3+ at high concentration displaced Ca2+ from alpha-amylase competitively. The equilibrium dialysis demonstrates that a-amylase has five Ca2+ -binding sites with different affinities. The fluorescence titration shows that Ce3+ can bind to Ca2+ - binding sites.