Abstract
A simple and specific method for assaying lipoprotein lipase activity is described. Postheparin plasma, heart homogenates, or extracts of acetone powder of adipose tissue were incubated with a triolein-coated Celite substrate, and enzyme activity was determined from the rate of free fatty acid (FFA) release in the incubation system. FFA release was linear for 30 min, and was proportional to protein concentration in the incubation system. FFA release was decreased by addition of deoxycholate or Triton X-100. Increasing the concentration of heparin in the incubation system caused a gradual decrease in FFA release by postheparin plasma and increases in activity of heart homogenates and adipose tissue lipoprotein lipase. The Celite substrate was found to be satisfactory for assaying pancreatic lipase activity as well.
Highlights
After temperature equilibration 1 ml of postheparin plasma (PHP) or aliquots of tissue extracts were added to each flask and incubation was continued for the desired time period. 1-ml aliquots were removed at convenient time intervals (I-ml serological pipettes were used, since narrow-tipped pipettes may on occasion become clogged with substrate) and they were immediately transferred to test tubes containing 5 ml of isopropanol-heptane-2 N HzS04 40 :10:1 (v/v/v) for fatty acid determinations by the method of Dole [10]
By increasing the amount of substrate in the incubation medium (Fig. 1 C) no increment in free fatty acid (FFA) release was observed beyond 90 mg; the amount employed in the final assay system, 120 mg, was not rate limiting
The results showed that Celite had no effect on plasma lipoprotein lipase (LPL)
Summary
Hospital Central de las Fuerzas Armadas, and Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas, Venezuela. SUMMARY A simple and specific method for assaying lipoprotein lipase activity is described. Postheparin plasma, heart homogenates, or extracts of acetone powder of adipose tissue were incubated with a triolein-coated Celite substrate, and enzyme activity was determined from the rate of free fatty acid (FFA) release in the incubation system. FFA release was linear for 30 min, and was proportional to protein concentration in the incubation system. FFA release was decreased by addition of deoxycholate or Triton X-100. Increasing the concentration of heparin in the incubation system caused a gradual decrease in FFA release by postheparin plasma and increases in activity of heart homogenates and adipose tissue lipoprotein lipase. The Celite substrate was found to be satisfactory for assaying pancreatic lipase activity as well
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