Intestinal cholesterol esterase: intracellular enzyme or contamination of cytosol by pancreatic enzymes?
Intestinal cholesterol esterase: intracellular enzyme or contamination of cytosol by pancreatic enzymes?
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DOI：
10.1016/s0022-2275(20)37813-5
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发表时间：
1984-04
影响因子：
6.5
通讯作者：
F. Field
中科院分区：
文献类型：
--
作者：
F. Field
对家兔肠道胆固醇酯酶的定位进行了重新评价。在三个不同的实验，旨在消除污染粘液和胰腺酶从小肠腔，它被观察到，胆固醇酯酶和淀粉酶的活性在肠胞质溶胶和整个匀浆平行的方式下降。在制备胞质溶胶之前，仔细擦拭肠粘膜上的粘液后，淀粉酶和胆固醇酯酶活性降低了7倍。细胞质中两种酶总活性的回收率约为15%。当小肠内腔充满磷酸盐缓冲液，并在37 ℃孵育20分钟，胆固醇酯酶和淀粉酶的活性从这段制备的胞质溶胶进一步下降。此外，淀粉酶和胆固醇酯酶的活性完全恢复管腔。如果使用二硫苏糖醇作为粘液溶解剂来制备用于分离肠细胞的肠粘膜，则消除胞质溶胶中的淀粉酶和胆固醇酯酶活性。在从这些肠段制备的全匀浆中，约10-15%的总胆固醇酯酶活性保留。这种活动，这不能占胰腺污染，与肠核和细胞碎片。孕酮，炔雌醇，25-羟基胆固醇调节微粒体酰基辅酶A：胆固醇酰基转移酶的活性，并引起类似的方向变化，在离体肠细胞的胆固醇酯合成率。然而，这些相同的甾醇，未能影响细胞溶质胆固醇酯酶活性在体外。
The location of cholesterol esterase in rabbit intestine was re-evaluated. In three different experiments that were designed to eliminate contaminating mucus and pancreatic enzymes from the lumen of the small intestine, it was observed that the activities of cholesterol esterase and amylase in intestinal cytosol and whole homogenate decreased in parallel fashion. After the mucus was carefully wiped from the intestinal mucosa prior to the preparation of cytosol, amylase and cholesterol esterase activities decreased sevenfold. The recovery of the total activity of both enzymes in the cytosol was approximately 15%. When the lumen of the small intestine was filled with phosphate buffer and incubated at 37 degrees C for 20 min, cholesterol esterase and amylase activities in the cytosol prepared from this segment were further decreased. Moreover, the activities of amylase and cholesterol esterase were completely recovered from the lumen. Amylase and cholesterol esterase activities in the cytosol were eliminated if dithiothreitol was used as a mucolytic agent to prepare intestinal mucosa for the isolation of intestinal cells. In whole homogenates prepared from these intestinal segments, approximately 10–15% of the total cholesterol esterase activity remained. This activity, which could not be accounted for by pancreatic contamination, was associated with intestinal nuclei and cellular debris. Progesterone, ethinyl estradiol, and 25-hydroxycholesterol regulated microsomal acyl CoA:cholesterol acyltransferase activity and caused similar directional changes in the rate of cholesteryl ester synthesis in isolated intestinal cells. These same sterols, however, failed to affect cytosolic cholesterol esterase activity in vitro.