London J, Hausman S Z, Thompson J
J Bacteriol. 1985 Sep;163(3):951-6. doi: 10.1128/jb.163.3.951-956.1985.
One of the key components of the futile xylitol cycle of Lactobacillus casei Cl-16 is a phosphatase which dephosphorylates xylitol 5-phosphate to xylitol prior to the expulsion of the pentitol from cells. This enzyme has been partially purified and characterized. The phosphatase is active against a variety of four-, five-, and six-carbon sugars and sugar alcohols phosphorylated at the terminal 4, 5, and 6 positions, respectively, but exhibits little or no affinity for substrates phosphorylated at the C-1 position. The enzyme has an apparent molecular weight of 62,000 and a pH optimum between 5.5 and 6, and it requires a divalent cation (Mg2+) for maximal activity. A single protein band, exhibiting phosphatase activity, was excised from polyacrylamide gels and used to prepare antiphosphatase sera in rabbits. The antiserum was used to detect the enzyme on polyacrylamide gels and to determine the molecular weight of the monomer on sodium dodecyl sulfate-polyacrylamide gels. With a subunit molecular weight of 32,000, the native enzyme appears to be a dimer. Phosphatase activity and substrate specificity are regulated by some component associated with the cytoplasmic membrane.
干酪乳杆菌Cl-16无效木糖醇循环的关键成分之一是一种磷酸酶，它在戊糖醇从细胞排出之前将5-磷酸木糖醇去磷酸化为木糖醇。这种酶已被部分纯化并进行了特性鉴定。该磷酸酶对分别在末端4、5和6位磷酸化的多种四碳、五碳和六碳糖及糖醇具有活性，但对在C-1位磷酸化的底物几乎没有或没有亲和力。该酶的表观分子量为62,000，最适pH在5.5至6之间，并且需要二价阳离子（Mg2+）以达到最大活性。从聚丙烯酰胺凝胶中切下一条显示磷酸酶活性的单一蛋白带，并用于在兔中制备抗磷酸酶血清。该抗血清用于在聚丙烯酰胺凝胶上检测该酶，并在十二烷基硫酸钠-聚丙烯酰胺凝胶上确定单体的分子量。亚基分子量为32,000，天然酶似乎是二聚体。磷酸酶活性和底物特异性受与细胞质膜相关的某些成分调节。
