Effects of two albumins and two detergents on the activity of bovine milk lipoprotein lipase against very low density and high density lipoprotein lipids

Abstract

In this study we have determined the effects of two commercial albumin preparations (Sigma and Pentex albumins) and two detergents (sodium deoxycholate and Triton X-100) on the activity of lipoprotein lipase purified from bovine milk against biosynthetically labeled triacylglycerol in very low density lipoprotein and biosynthetically labeled phosphatidylcholine in very low density and high density lipoproteins. Pentex albumin decreased the activity of lipoprotein lipase in all assays to about one-fourth to one-third of that observed with Sigma albumin. Quantitative differences were observed in the distribution of labeled surface constituents ( 32P-labeled phospholipids, [ 3H]cholesterol and 125I-labeled apolipoprotein C) among density fractions during lipolysis of very low density lipoprotein carried out in the presence of Pentex or Sigma albumins. With Pentex albumin, more phospholipids and apolipoprotein C distributed to the density fraction of d 1.04−1.21 g/ ml than with Sigma albumin. Sodium deoxycholate at a concentration of up to 2 mM had little effect in all assays. Triton X-100 decreased the activity of lipoprotein lipase against very low density lipoprotein lipids but increased the activity of the enzyme against high density lipoprotein lipids. The study has thus demonstrated marked quantitative differences of lipoprotein lipase activities when determined under slightly differing incubation conditions.