Influence of pH on the hydrolysis of p-nitrophenyl maltodextrins by alpha-amylase 2 from malted barley

The action of barley malt alpha-amylase 2 (E.C. 3.2.1.1) on p-nitrophenyl d erivatives of maltodextrins was studied at pH 4.8, 6.0 and 7.8. Distributio ns of products from any one substrate changed little with pH, but a differe nce in behaviour was observed at pH 4.8 between longer and shorter substrat es. With long substrates, such as p-nitrophenyl alpha-malto-octaoside, the enzyme showed high activity at pH 4.8 and 6.0, while for shorter substrates , enzyme activity was much less at pH 4.8 than at 6.0. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.