We have developed a novel enzymatic cycling method that uses purine nucleoside phosphorylase (PNP) (EC 2.4.2.1) from Bacillus sp. to measure inorganic phosphate. The method utilizes the reversibility of the PNP reaction, in which the forward and reverse reactions are catalyzed in the presence of an excess amount of inosine and guanine, respectively, a principle similar to that previously demonstrated with creatine kinase (CK). Real-time detection was accomplished by coupling the reaction with commercially available xanthine dehydrogenase (EC 1.17.1.4) in the presence of NAD⁺. The efficiency of the cycling reaction per unit of enzyme (U ml⁻¹) was remarkably higher than the CK.

中文翻译：

---

嘌呤核苷磷酸化酶循环法测定无机磷酸盐的研究进展

我们已经开发了一种新型的酶循环方法，该方法使用了芽孢杆菌属的嘌呤核苷磷酸化酶（PNP）（EC 2.4.2.1）。测量无机磷酸盐。该方法利用了PNP反应的可逆性，其中正向反应和反向反应分别在过量肌苷和鸟嘌呤的存在下进行催化，其原理与以前用肌酸激酶（CK）证明的原理相似。在NAD ⁺存在下，通过将反应与市售的黄嘌呤脱氢酶（EC 1.17.1.4）偶联来完成实时检测。每单位酶（U ml ^-1）的循环反应效率显着高于CK。