Preparation and properties of immobilized lipoprotein lipase

Purified bovine milk lipoprotein lipase has been covalently attached to CH-Sepharose with water-soluble carbodiimide. The immobilized enzyme retained enzymic activity and was stimulated 7-fold by the addition of human apolipoprotein C-II. Both [3H]heparin and 125I-labeled apolipoprotein C-II bound to the immobilized enzyme; unlabeled heparin and apolipoprotein C-II competed for binding of their respective labeled compounds. Apolipoprotein C-II did not compete for binding of [3H]heparin and vice versa. Human apolipoprotein C-III did not bind to the immobilized enzyme nor did it compete for apolipoprotein C-II binding. We conclude from these studies that both apolipoprotein C-II and heparin interact with immobilized lipoprotein lipase and that they have different binding sites.