[The interaction of Ca2+ and heparin in the activation of lipoprotein lipase from adipose tissue (author's transl)].

The effect of calcium on the activation of lipoprotein lipase by heparin was studied using ammonia buffer extracts of acetone powder from guinea pig adipose tissue as the lipoprotein lipase source. Lipase activity was assayed with an artificial triglyceride emulsion that had been activated with rat high density lipoproteins. The addition of Ca2+ (2mM) alone increased the lipoprotein lipase activity about 2.5- to 3.5-fold, but heparin (1 unit/ml) alone had little effect. When both Ca2+ and heparin were added to the assay medium, the activity was increased to 4- to 5- fold above control values. When Ca2+ in the assay medium was sequestrated by EGTA, these increases by Ca2+ and heparin were completely abolished. The results suggest that the presence of Ca2+ is a prerequisite for the activation of lipoprotein lipase by heparin. Gel filtration of the mixture of acetone poder extracts and [3H] heparin showed the enzyme bound [3H] heparin whether Ca2+ was present or not. In addition to lipoprotein lipase, there were proteins in adipose tissue extracts which had an affinity for heparin.