Lorenz B, Müller W E, Kulaev I S, Schröder H C
Institut für Physiologische Chemie, Universität, Mainz, Federal Republic of Germany.
J Biol Chem. 1994 Sep 2;269(35):22198-204.
An exopolyphosphatase (polyphosphate phosphohydrolase; EC 3.6.1.11) activity that cleaves inorganic polyphosphates to orthophosphate has been purified to apparent homogeneity (> 95% pure) from Saccharomyces cerevisiae. The exopolyphosphatase is a monomeric protein with a polypeptide molecular mass of 28 kDa. The enzyme, which can be stabilized in the presence of Triton X-100, has a pH optimum of 7.5 and requires, for maximal activity, Co2+ or Mg2+ ions. In the absence of these ions, the exopolyphosphatase binds to polyphosphate but does not degrade it, allowing affinity purification of the enzyme on a polyphosphate-modified zirconia support. o-Vanadate, Cu2+, and Ca2+ are effective inhibitors of the exopolyphosphatase. The enzyme preferentially hydrolyzes linear polyphosphates in a non-processive manner; pyrophosphate as well as cyclic tri- and tetrametaphosphate are degraded only at very low rates, whereas ATP is not split by the exopolyphosphatase. The only product formed by the action of the enzyme is orthophosphate.
一种将无机多聚磷酸盐裂解为正磷酸盐的外切多聚磷酸酶（多聚磷酸盐磷酸水解酶；EC 3.6.1.11）活性已从酿酒酵母中纯化至表观均一性（纯度>95%）。该外切多聚磷酸酶是一种单体蛋白，多肽分子量为28 kDa。该酶在Triton X-100存在下可稳定存在，最适pH为7.5，最大活性需要Co2+或Mg2+离子。在没有这些离子的情况下，外切多聚磷酸酶与多聚磷酸盐结合但不降解它，从而可以在多聚磷酸盐修饰的氧化锆载体上对该酶进行亲和纯化。偏钒酸盐、Cu2+和Ca2+是外切多聚磷酸酶的有效抑制剂。该酶以非连续方式优先水解线性多聚磷酸盐；焦磷酸盐以及环状三聚和四聚偏磷酸盐仅以非常低的速率降解，而ATP不会被外切多聚磷酸酶裂解。该酶作用形成的唯一产物是正磷酸盐。
