HUMAN PANCREATIC ALPHA-AMYLASE .2. EFFECTS OF PH, SUBSTRATE AND IONS ON ACTIVITY OF ENZYME

  • 1 January 1977
    • journal article
    • research article
    • Vol. 7  (4) , 310-317
Abstract
Purified human pancreatic .alpha.-amylase (.alpha.-1,4-glucan 4-glucano-hydrolase, EC 3.2.1.1) was stable over a wide range of pH values (5.0-10.5) with an optimal pH for the enzymatic activity of 7.0. The Km of the enzyme at optimal pH and assay conditions was 2.51 mg/ml for soluble starch. Halide ions were required for the activity of the enzyme whereas sulfate and nitrate were not. The order of effectiveness of activation was: Cl- > Br- > I- > F-. Ca and Mg were activators at concentrations of 0.001 M and 0.005 M, respectively, but exhibited inhibitory effects at concentrations higher than 0.005 M. At 0.01 M EDTA concentration the enzymatic activity on 7 min incubation, was inhibited up to 96%. The inhibition of EDTA and Ca could be reversed on addition of Ca and EDTA, respectively.