Preparation of Chylomicrons and VLDL with Monoacid-Rich Triacylglycerol and Characterization of Kinetic Parameters in Lipoprotein Lipase-Mediated Hydrolysis in Chickens

Manuscript received 17 December 1997. Initial reviews completed 26 January 1998. Revision accepted 4 September 1998.

Kan Sato^*, , Toshihiro Takahashi^*, Yuji Takahashi, Hiroki Shiono, Norio Katoh, and Yukio Akiba^*

^* Department of Animal Science, Faculty of Agriculture, Tohoku University, Sendai-shi 981, Japan and  National Institute of Animal Health, Tsukuba-shi 305, Japan

To identify the substrate specificity of lipoprotein lipase (LPL) for triacylglycerol-rich lipoproteins with monoacid-rich triacylglycerols, monoacid-rich lipoproteins were prepared and kinetic parameters of LPL were characterized. Male broiler chickens were fed 8 g/100 g fat diets differing only in the fat source: palm oil (tripalmitin-rich), olive oil (triolein-rich), safflower oil (trilinolein-rich) and linseed oil (trilinolenin-rich). After diets were fed for 3 d, chickens were starved for 2 d and then force-fed emulsions containing one of the monoacid-triacylglycerols: tripalmitin, triolein, trilinolein or trilinolenin. The triacylglycerols in chylomicrons and very low density lipoprotein (VLDL) of chickens force-fed tripalmitin, triolein or trilinolein contained the corresponding acid at more than 70% of total acids. Linolenic acid was incorporated into chylomicrons and VLDL to a lower extent (51.2 and 57.2%, respectively) in chickens force-fed trilinolein. Major apolipoproteins and lipid compositions were not significantly different among all lipoproteins isolated from chickens fed the different fats. Vmax of LPL was significantly higher (P < 0.05) for palmitic acid-rich chylomicrons and VLDL and decreased with increasing chain length and unsaturation of monoacid: 16:0>18:1>18:2>18:3. The electron spin resonance analysis, order parameter (S), decreased with monoacid chain length and unsaturation. In addition, the Vmax of LPL increased linearly (P < 0.01, r = 0.912) with an increase in the palmitic acid content of the lipoprotein triacylglycerols. These findings suggest that lipoprotein catalysis by LPL is modulated by the palmitic acid content of the lipoprotein triacylglycerol, which affects the fluidity of lipoproteins.

The Journal of Nutrition Vol. 129 No. 1 January 1999, pp. 126-131
Copyright ©1999 by the American Society for Nutritional Sciences

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