INTERACTIONS OF LIPOPROTEIN-LIPASE WITH THE ACTIVE-SITE INHIBITOR TETRAHYDROLIPSTATIN (ORLISTAT)(R)
INTERACTIONS OF LIPOPROTEIN-LIPASE WITH THE ACTIVE-SITE INHIBITOR TETRAHYDROLIPSTATIN (ORLISTAT)(R)
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DOI：
10.1111/j.1432-1033.1994.tb18878.x
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发表时间：
1994-06-01
期刊：
影响因子：
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通讯作者：
OLIVECRONA, G
中科院分区：
文献类型：
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作者：
LOOKENE, A;SKOTTOVA, N;OLIVECRONA, G
脂蛋白脂酶（LPL）被低浓度的活性位点抑制剂四氢lipstatin（THL）迅速灭活。两亲物（例如长链脂肪酸）或脂质/水界面（脂肪乳剂）的存在是发生抑制所必需的。载脂蛋白Cn.在长链三酰甘油乳剂存在下，使最大灭活速率常数增加1.8倍，但在三丁酰甘油乳剂存在下没有效果。完全抑制的酶具有接近2的THL/LPL比率，表明LPL同源二聚体的两个亚基结合THL。THL-LPL复合物在低于pH 7.5时稳定。在较高的pH值下发生再活化，表明THL被酶缓慢地翻转。表观再活化速率常数增加约3倍的存在下的脂/水interfaces.Sucrose密度梯度离心显示，THL诱导LPL的四聚化。这种聚集在被抑制的酶的再活化时是可逆的。与肝素的结合不受THL的影响，相反，与脂滴和脂蛋白的结合增加，表明在抑制的LPL中的疏水区域的暴露。有人建议，THL诱导局部构象的变化，LPL，这可能涉及开放的假定的表面盖结构覆盖的活性位点。
Lipoprotein lipase (LPL) was rapidly inactivated by low concentrations of the active-site inhibitor tetrahydrolipstatin (THL). The presence of amphiphils (e.g. long-chain fatty acids) or of lipid/water interfaces (lipid emulsions) was required for inhibition to occur. Apolipoprotein Cn. increased the maximal inactivation rate constant by 1.8-fold in the presence of an emulsion of long-chain triacylglycerols, but had no effect in the presence of an emulsion of tributyrylglycerol. The fully inhibited enzyme had a ratio of THL/LPL of nearly 2, indicating that both subunits of the LPL homo-dimer bound THL. The THL-LPL complex was stable below pH 7.5. At higher pH reactivation occurred indicating that THL was slowly turned over by the enzyme. The apparent reactivation rate constant was increased about threefold by the presence of lipid/water interfaces.Sucrose density gradient centrifugation revealed that THL induces tetramerisation of LPL. This aggregation was reversible on reactivation of the inhibited enzyme. Binding to heparin was not affected by THL, In contrast, binding to lipid droplets and to lipoproteins was increased, indicating exposure of hydrophobic regions in the inhibited LPL. It is suggested that THL induces local conformational changes in LPL, which may involve opening of the putative surface lid structure which covers the active-site.