Koster A S, Frankhuijzen-Sierevogel A C, Noordhoek J
Biochem Pharmacol. 1985 Oct 1;34(19):3527-32. doi: 10.1016/0006-2952(85)90728-2.
The distribution of glucuronidation capacity along the rat intestine was investigated using mucosal cells, isolated from the small intestine, the caecum, and the colon plus rectum. The glucuronidation capacity for 1-naphthol decreases from 787 +/- 75 (duodenum) to 128 +/- 13 (colon plus rectum) pmoles/min X mg cell protein. The ratio between 1-naphthol and morphine glucuronidation was constant throughout the intestine (7.15 +/- 0.37). The distribution of maximal activity of UDP-glucuronosyltransferase in intestinal cell homogenates follows the same pattern. The maximal activity of UDPglucose dehydrogenase in homogenates corresponds closely to the glucuronidation rate in mucosal cells. The activity of beta-glucuronidase in intestinal cell homogenates is constant along the duodenum and jejunum but increases throughout the terminal ileum, caecum, colon and rectum. Subcellular fractionation studies using marker enzymes indicate that UDPglucose dehydrogenase and beta-glucuronidase are cytosolic enzymes in intestinal mucosal cells. Although UDP-glucuronosyltransferase activity is found in both the mitochondrial and the microsomal fractions, no indications for a mitochondrial localization of this enzyme can be found. Activity in the mitochondrial fraction appears to be due to endoplasmic reticulum, associated with the mitochondrial fraction.
利用从小肠、盲肠以及结肠加直肠分离出的黏膜细胞，研究了大鼠肠道中葡萄糖醛酸化能力的分布情况。1-萘酚的葡萄糖醛酸化能力从十二指肠的787±75皮摩尔/分钟×毫克细胞蛋白降至结肠加直肠的128±13皮摩尔/分钟×毫克细胞蛋白。在整个肠道中，1-萘酚与吗啡葡萄糖醛酸化之间的比率是恒定的（7.15±0.37）。肠道细胞匀浆中尿苷二磷酸葡萄糖醛酸基转移酶的最大活性分布遵循相同模式。匀浆中尿苷二磷酸葡萄糖脱氢酶的最大活性与黏膜细胞中的葡萄糖醛酸化速率密切相关。肠道细胞匀浆中β-葡萄糖醛酸酶的活性在十二指肠和空肠中保持恒定，但在回肠末端、盲肠、结肠和直肠中则逐渐增加。使用标记酶进行的亚细胞分级分离研究表明，尿苷二磷酸葡萄糖脱氢酶和β-葡萄糖醛酸酶是肠道黏膜细胞中的胞质酶。尽管在线粒体和微粒体部分均发现了尿苷二磷酸葡萄糖醛酸基转移酶的活性，但未发现该酶定位于线粒体的迹象。线粒体部分的活性似乎归因于与线粒体部分相关的内质网。
