Byrd J C, Fearney F J, Kim Y S
J Biol Chem. 1985 Jun 25;260(12):7474-80.
The nucleotide-sugar pyrophosphatase activity of rat small intestine was studied using GDP-[14C]Man as substrate. The highest specific activities in the gastrointestinal tract were in the proximal small intestine, with a preferential localization in villus tip cells. Purified brush-border membranes were highly enriched in nucleotide-sugar pyrophosphatase. After the enzyme was solubilized with detergent and purified 180-fold, it hydrolyzed FAD and p-nitrophenyl-5'-thymidylate, as well as nucleotide sugars. That the same enzyme, a 5'-nucleotide phosphodiesterase, is responsible for nucleotide-sugar pyrophosphatase, phosphodiesterase I, and FAD pyrophosphatase activities is indicated by: co-migration in electrophoresis, parallel thermal inactivation, competitive inhibition studies, and similar regional, cellular, and subcellular localizations.
以GDP-[14C]甘露糖为底物，对大鼠小肠的核苷酸糖焦磷酸酶活性进行了研究。胃肠道中比活性最高的部位是小肠近端，且优先定位于绒毛顶端细胞。纯化的刷状缘膜富含核苷酸糖焦磷酸酶。用去污剂溶解该酶并纯化180倍后，它能水解FAD和对硝基苯基-5'-胸苷酸，以及核苷酸糖。以下方面表明，同一种酶，即5'-核苷酸磷酸二酯酶，负责核苷酸糖焦磷酸酶、磷酸二酯酶I和FAD焦磷酸酶的活性：电泳中共迁移、平行热失活、竞争性抑制研究，以及相似的区域、细胞和亚细胞定位。
