Lipoprotein lipase from bovine milk. Isolation procedure, chemical characterization, and molecular weight analysis

Abstract

Lipoprotein lipase of high purity has been isolated from bovine milk by affinity chromatography on heparin-Sepharose, adsorption to Cgamma-aluminum hydroxide gel, and intervent dilution chromatography on heparin-Sepharose. Chemical analysis shows that the enzyme is a glycoprotein containing 8.3% carbohydrate. The monomer molecular weight, determined under reducing conditions in 6.6 M guanidine HCl by sedimentation equilibrium ultracentrifugation and analytical gel chromatrgraphy, is 48,300 and 50,800, respectively. Analyses of the sedimentation coefficient (SO20,w=5.40 S) and the diffusion coefficient (DO20,w=48.8 mum2/s) in a buffer of physiological pH and ionic strength yield a molecular weight of 96,900. In solution, the native enzyme thus appears to be a dimer of presumably identical subunits.