Purification of canine post-heparin hepatic lipase.

A method for the purification of canine hepatic lipase from post-heparin hepatic venous blood plasma was developed and found applicable to mixed venous post-heparin plasma. The method employs sequential (NH4)2SO4 fractionation, heparin-Sepharose chromatography at pH 8.8 and, finally, adsorption to antiserum prepared against dog pre-heparin plasma. The lipase was purified 10,000-fold. The specific activity assayed with Intralipid as substrate was 840 mumol free fatty acid h-1 . mg-1. Enzyme recovery was 20%. Upon electrophoresis of the purified lipase in polyacrylamide gel containing SDS, a major protein-staining band with an apparent molecular weight of 60,000 was consistently found. This component accounted for 85-90% of the protein applied to the gel, and by amino acid analysis appeared to be distinct from canine antithrombin III, a protein thought to contaminate hepatic lipase purified by earlier methods.