Purification and characterization of α-amylases from the intestine and muscle of Ascaris suum (Nematoda).

α-Amylase (EC 3.2.1.1) was purified from the muscle and intestine of the parasitic helminth of pigs Ascaris suum. The enzymes from the two sources differed in their properties. Isoelectric focusing revealed one form of α-amylase from muscles with pI of 5.0, and two forms of amylase from intestine with pI of 4.7 and 4.5. SDS/PAGE suggested a molecular mass of 83 kDa and 73 kDa for isoenzymes of α-amylases from intestine and 59 kDa for the muscle enzyme. α-Amylase from intestine showed maximum activity at pH 7.4, and the enzyme from muscle at pH 8.2. The muscle enzyme was more thermostabile than the intestinal α-amylase. Both the muscle and intestine amylase lost half of its activity after 15 min at 70°C and 50°C, respectively. The Km values were: for muscle amylase 0.22 μg/ml glycogen and 3.33 μg/ml starch, and for intestine amylase 1.77 μg/ml glycogen and 0.48 μg/ml starch. Both amylases were activated by Ca2+ and inhibited by EDTA, iodoacetic acid, p-chloromercuribenzoate and the inhibitor of α-amylase from wheat. No significant differences were found between the properties of α-amylases from parasites and from their hosts.