PURIFICATION AND PROPERTIES OF GALACTOLIPASE

1. 1. Isolation and purification of the mono- and digalactolipase activity from runner-bean leaves (Phaseolus multiflorus Lam.) resulted in one protein which contained both galactolipase activities. 2. 2. The ratio of the specific activities of the monogalactolipase activity to the digalactolipase activity was 2:1. 3. 3. The isoelectric point of the protein with both galactolipase activities is pH 7.0. 4. 4. After incubation no detectable amounts of a lyso compound of the galactolipids were observed in the reaction mixtures. 5. 5. Experiments concerning the enzyme stability as affected by temperature and storage demonstrated that galactolipase from runner-bean leaves is quite stable. 6. 6. The Michaelis-Menten constants for the mono- and digalactolipase activities are 0.65 mM and 0.31 mM, respectively. 7. 7. The molecular weight of galactolipase is 110 000. 8. 8. Galactolipase is activated by the addition of strong reductants. 9. 9. Galactolipase is completely inhibited by cysteine. © 1969.