The Purification of a Lipoprotein Lipase from Bovine Skim Milk

Abstract

Abstract The purification of a lipase from skim milk is described. The enzyme had the characteristics of a lipoprotein lipase, i.e. its activity against emulsified long chain triglyceride was stimulated more than 20-fold by addition of suitable amounts of serum to the assay system and the activity was almost completely inhibited by 1 m NaCl. After an initial fractionation of the skim milk, the main purification was obtained by affinity chromatography on Sepharose 4B with covalently linked heparin. The preparation obtained was purified 5,000- to 7,000-fold. Gel electrophoresis of this preparation in urea or in sodium dodecyl sulfate revealed one major component which stained for protein and for carbohydrate and which comprised more than 80% of the total protein. The apparent minimum molecular weight of this component was 62,000 to 66,000 as determined by electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate.