鸭血清脂蛋白的研究 Ⅷ.鸭HDL—apoCⅡ的生物活性测定及其体外代谢研究

Studies on Duck Serum Lipoproteins Ⅷ. Studies on Biological Activity and Metabolism of HDL-apo CⅡ in vitro

用肝素-Sepharose CL-6B亲合柱层析法分离牛奶LPL后,测定鸭HDL-apo CⅡ对LPL的激活作用。结果表明其激活作用很强,2.9μg即可有效地激活LPL,11.8μg为最适激活量;用^(125)I-HDL-apo CⅡ法的实验表明鸭HDL-apo CⅡ与VLDL和HDL的单独结合率分别为59.9%和57.1%两者基本相同。其在HDL和VLDL间的分布率分别为98.9%和1.1％;鸭HDL-apo CⅡ在VLDL和HDL间的转移是双向的,从HDL向VLDL的转移率为6.8％;从VLDL向HDL的转移率为88.2％。后者是转移的主方向。

Having fed Beijing duck with high fat and cholesterol diet, no typicalatherosclerotic plaque was noticed except for increase of strum HDL-chole-sterol. The authors suggest that ducks earring exogenous cholesterol withHDL are insusceptible to atherosclerosis. Based on this idea, studies weremale on properties and metabolism of duck serum HDL ,especially on apo-lipoproteins for illustration of role of HDL in anti-atherogenesis. In thispaper, we studied biological activity and metabolism of HDL-apo CⅡ invitro.LPL was isolated from milk with affinity chromatography on heparin-sepharose CL-6B. Cofactor activity of duck HDL-apo CⅡ for LPL was assayed. It was found that apo CⅡ was very effective and 2,9 μg of apo CⅡ could activate milk LPL efficiently, 11.8 μg being the optimum amount,but apo AI had no such activation. Studies with 125I-apo CⅡ on metabolism of duck HDL-apo CⅡ were performed in vitro, suggesting that it could bind to VLDL as well as HDL and distributed mainly on HDL, its transfer between HDL and VLDL being bidirectional and that from VLDL to HDL as the major direction.