Sato K, Akiba Y, Horiguchi M
Department of Animal Science, Faculty of Agriculture, Tohoku University, Sendai, Japan.
Comp Biochem Physiol A Physiol. 1997 Nov;118(3):855-8. doi: 10.1016/s0300-9629(97)00218-1.
Chemical characterization of chicken and rat lipoprotein lipase (LPL) was carried out following purification of LPL. Molecular weight and isoelectric point of both purified enzymes were determined to be 60 KDa and pH 4, while optimum temperature and pH to yield the maximal activity were about 37 degrees C and pH 8.5. Metallic ions, NaCl and protamine sulfate reduced, and heparin increased, both LPL activities. Michaelis constants for LPLs determined with triolein emulsion as the substrate were 0.98 and 1.57, and those of Vmax were 379.2 and 181.3, in chickens and rats, respectively. Triton WR-1339 caused mixed-type inhibition in rat, but inhibited chicken LPL noncompetitively. In LPLs of chickens and rats, values of Ki were 66.7 and 36.4 with triolein emulsion as the substrate, and 832.4 and 66.0 with respective VLDL as the substrate. These results show species difference between chickens and rats in the affinity to lipoproteins of LPL and inhibition of LPL by Triton WR-1339.
在脂蛋白脂肪酶（LPL）纯化后，对鸡和大鼠的脂蛋白脂肪酶进行了化学特性分析。两种纯化酶的分子量和等电点分别测定为60 kDa和pH 4，而产生最大活性的最佳温度和pH约为37℃和pH 8.5。金属离子、氯化钠和硫酸鱼精蛋白降低了LPL的活性，而肝素则增加了LPL的活性。以三油酸甘油酯乳剂为底物测定的鸡和大鼠LPL的米氏常数分别为0.98和1.57，Vmax分别为379.2和181.3。Triton WR-1339对大鼠产生混合型抑制，但对鸡LPL产生非竞争性抑制。在鸡和大鼠的LPL中，以三油酸甘油酯乳剂为底物时，Ki值分别为66.7和36.4，以各自的极低密度脂蛋白（VLDL）为底物时，Ki值分别为832.4和66.0。这些结果表明，鸡和大鼠在LPL对脂蛋白的亲和力以及Triton WR-1339对LPL的抑制作用方面存在种属差异。
