Liposome-incorporated enzymes: studies on amylase

Alpha-amylase (EC 3.2.1.1) from hog pancreas was incorporated into artificial phosphatidylcholine and phosphatidylserine liposomes. To kinetically follow the enzyme-catalyzed hydrolysis of amylose the liposome-bound amylase was incubated in a medium containing amylose-iodine substrate. The reaction was studied at different concentrations of amylose and at different ionic strengths. Activation of amylase incorporated into liposomes by chloride ions varies with the type of phospholipid utilized to prepare the liposomes. Whe amylase bound to negative charged liposomes was used, a sigmoidal relationship between the reaction velocity and substrate concentration was found. Incorporation into liposomes protects amylase from heat inactivation.