Encapsulation and stimulated release of enzymes using lecithin vesicles

Summary Lecithin vesicles prepared by dehydration-rehydration (DR) were used to encapsulate enzymes (lysozyme and pepsin). The encapsulating efficiency was highest when the pH was close to the isoelectric point of each enzyme. Vesicles stored in suspension at 10°C for up to 21 days showed no release of enzymes. Acidic pH at 10°C and 25 mM Ca2+ at 10°C or 37°C produced pulse-like release of 17–35%, while acidic pH at 37°C produced pulse-like release followed by slow release up to 100%, and Tween 80 induced steady release from the beginning. The hydrolysis pattern of a protein by pepsin released from DR vesicles for 142 hr was similar to that obtained by the same total amount of fresh pepsin solution added stepwise, in proportion, indicating that the pepsin retains its activity throughout the period of encapsulation. Vesicles prepared by processing of lecithin-enzyme solution by a homogenizer (MicrofluidizerTM) were also characterized and found effective.