2.3.2.2. Determination of the activity of α-amylase. The enzymatic activity of α-amylase was determined according to Morishita, et al. (2000). A reaction mixture consisting of 500 μL of G3 CNP at concentrations ranging from 0.6 to 3.0 mM; 400 μL of 13.1 mg mL1 bile acid extract (equivalent to 18.7 mM cholic acid in the total mixture), 500 μL of each PP solution at concentrations ranging from 60 to 300 μg mL1 , and 100 μL of a working solution of α-amylase of 150 U mL1 (one unit is the amount of enzyme required to convert 1 μmol of G3 CNP) was prepared. All of the solutions were prepared in 20 mM phosphate buffer pH 7.0 containing 10 mM NaCl and 15% (v/v) glycerol. The mixture was incubated at 37 1C and the absorbance of the CNP produced was measured at 405 nm every 5 s throughout 60 s.