Barter P J, Gooden J M, Rajaram O V
Atherosclerosis. 1979 Jun;33(2):165-9. doi: 10.1016/0021-9150(79)90113-8.
Low density lipoproteins (LDL), endogenously labelled with 3H in the triglyceride moiety, were isolated from rabbit serum and subsequently incubated in vitro at 37 degrees C with unlabelled preparations of rabbit high density lipoproteins (HDL) or very low density lipoproteins (VLDL). In incubations performed in the presence of phosphate buffer, there was no significant transfer of [3H]triglyceride from LDL to either HDL or VLDL; but when rabbit lipoprotein-free serum (the dialysed 1.21 g/ml infranatant) was added, transfer was apparent to both HDL and VLDL. The triglyceride transferring activity of the lipoprotein-free serum was abolished by heating at 85 degrees C for 10 min; all the transferring activity was found in the fraction which precipitated with ammonium sulphate at a concentration of less than 50% saturation. In direct contrast to the rabbit studies, rat serum failed to show a comparable process of triglyceride transfer. In subsequent experiments, mixtures of labelled LDL and unlabelled VLDL isolated either from rabbits or from rats were incubated with lipoprotein-free rabbit, rat or human serum. The lipoprotein-free serum of both the rabbit and man was effective in promoting transfer of 30--50% of LDL [3H]triglyceride into VLDL, regardless of the species origin of the lipoproteins. By contrast the lipoprotein-free serum of rats was only slightly more effective than buffer alone in promoting such transfers. It has been concluded that rabbit and human serum contains a triglyceride transferring factor of far greater activity than that in rat serum.
从兔血清中分离出在甘油三酯部分内源性标记有³H的低密度脂蛋白（LDL），随后于37℃在体外与未标记的兔高密度脂蛋白（HDL）或极低密度脂蛋白（VLDL）制剂一起孵育。在存在磷酸盐缓冲液的孵育中，[³H]甘油三酯从LDL向HDL或VLDL均无明显转移；但加入无脂蛋白兔血清（经透析的1.21 g/ml下层清液）时，向HDL和VLDL的转移均很明显。无脂蛋白血清的甘油三酯转移活性在85℃加热10分钟后被消除；所有转移活性均存在于硫酸铵饱和度小于50%时沉淀的部分。与兔的研究形成直接对比的是，大鼠血清未显示出类似的甘油三酯转移过程。在随后的实验中，将从兔或大鼠分离出的标记LDL和未标记VLDL的混合物与无脂蛋白的兔、大鼠或人血清一起孵育。兔和人的无脂蛋白血清均能有效地促进30 - 50%的LDL [³H]甘油三酯转移至VLDL，而不论脂蛋白的物种来源。相比之下，大鼠的无脂蛋白血清在促进此类转移方面仅比单独的缓冲液略有效。得出的结论是，兔和人血清中含有的甘油三酯转移因子的活性远高于大鼠血清中的活性。
