DEMONSTRATION OF AN INTESTINAL MONOGLYCERIDE LIPASE - AN ENZYME WITH A POSSIBLE ROLE IN INTRACELLULAR COMPLETION OF FAT DIGESTION
DEMONSTRATION OF AN INTESTINAL MONOGLYCERIDE LIPASE - AN ENZYME WITH A POSSIBLE ROLE IN INTRACELLULAR COMPLETION OF FAT DIGESTION
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DOI：
10.1172/jci104705
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发表时间：
1963-01-01
影响因子：
15.9
通讯作者：
ISSELBACHER, KJ
中科院分区：
文献类型：
--
作者：
SENIOR, JR;ISSELBACHER, KJ
An intestinal lipase has been demonstrated in homo-genates and subcellular particles of rat intestinal epithelial cells. This lipase exhibits prominent specificity for monoglycerides, and is much less active upon the di- or triglycerides of long-chain fatty acids. A maximal hydrolytic activity was found for monoglycerides of intermediate chain length, i.e., from 8 to 12 carbon atoms in the saturated fatty acyl chain. Unsaturated long-chain monoglycerides were split at rates comparable to those for saturated monoglycerides of shorter chain length. A survey of the cell fractions showed the monoglyceride lipase activity to be concentrated primarily in the microsomal and mitochondrial fractions, with considerably lower specific activities present in the cell sap and isolated brush borders. Fluoride and EDTA (ethylenediamine tetraacetic acid) did not inhibit the enzyme activity. The intestinal monoglyceride lipase was distinct and different from pancreatic lipase in (a) its specificity for monoglycerides rather than triglycerides, (b) its ability to catalyze hydrolysis of ester bonds on the [beta]- as well as the [alpha]-hydroxyl groups of glycerides, and (c) its activity upon dissolved rather than suspended substrates. Other differences appear to exist in the effect of inhibitors, pH optima, and chain-length specificity, but further studies are necessary when purer enzyme preparations are obtained. This enzyme may function in the intracellular completion of fat digestion before the synthesis of chylomicrons by the intestinal mucosa.
