Characterization of a fluorometric method for lipoprotein lipase

A fluorometric assay for determining lipoprotein lipase (LPL) activity is described. Dibutyrilfluorescine (DBF) was used as substrate for the enzyme and the fluoresceine liberated by enzymatic hydrolysis of the substrate was measured. Extracts of acetone powder from adipose tissue as an enzyme source showed characteristics of lipoprotein lipase activity, i.e., inhibition by NaCl and optimum activity in alkaline pH. There was close agreement in LPL activity when the same sample was measured simultaneously using either dibutyrilfluorescine or tri[9,10(3)H]oleylglycerol as substrate. The extent of inhibition of lipoprotein lipase by NaCl was similar with both methods. The fluorometric method detected changes in LPL activity in heart and adipose tissue related to the nutritional status of the animal with the same specificity and sensitivity than did the radioactive method. The fluorometric method is as sensitive, less expensive and less time consuming than the radioactive method.