Reassociation of Deoxyribonuclease Ii with the Lysosomal Membrane Isolated from Porcine Spleen

Dnase II, bound to the lysosomal membrane of porcine spleen, can be extracted fom the membrane with 0.4 M NaCl. Reassociation of DNase II with the salt-extracted lysosomal membrane is readily accomplished in 0.01 M sodium acetate ( pH 4.5). The reassociable amount of DNase II is approximately equal to the extractable amount. The capacity of the lysosomal membrane to bind DNase II is unaffected by the subtilin treatment of the membrane. Phosphotidyl serine can bind DNase II as well, but with a much higher capacity. The erythrocyte plasma membrane on the other hand binds only 20% of DNase II bound to the lysosomal membrane. The DNase II activity can be eluted from a column of lysosomal membrane entrapped in 2% agarose and the elution parttern is very similar to that of CM-cellulose chromatography of DNsse II, suggesting that electrostaatic interaction may play an importaaant role in the binding. The pH- reassociation profile is bell-shaped and is similar to the pH-activity profile of DNase II, having a maximum near pH 5. Under nondenaturing condition, the dissociated a and b subuints of DNase II cannot be reassocited to regain the enzymatic activity with or without the lysosomal membrane