Purification from human plasma of a heparin-released lipase with activity against triglyceride and phospholipids

A triglyceride lipase different from lipoprotein lipase, but measurable only after intravenous heparin injection, has been isolated from human plasma by sequential use of heparin-Sepharose and concanavalin A-Sepharose affinity chromatography. Using these procedures, phospholipase A1 activity was found to chromatograph identically with the triglyceride lipase. The constancy of the ratio of activities after isoelectric focusing (pI 4.1) and during thermal deactivation indicates that this enzyme has hydrolase activity against both triglycerides and phospholipids. This conclusion was supported further by the homogeneity of the protein as indicated by sodium dodecyl sulfate polyacrylamide gel electrophoresis.