净化和属性inosine-guanosine磷酸化酶的大肠杆菌k - 12。
文章的细节
-
引用
复制到剪贴板 -
Koszalka GW, Vanhooke J,短SA,大厅WW
净化和属性inosine-guanosine磷酸化酶的大肠杆菌k - 12。
J Bacteriol。1988年8月,170 (8):3493 - 8。
- PubMed ID
-
3042752 (在PubMed]
- 文摘
-
xanthosine-inducible酶,inosine-guanosine磷酸化酶,部分纯化菌株大肠杆菌的k - 12缺乏deo-encoded嘌呤核苷磷酸化酶。Inosine-guanosine磷酸化酶有粒子的重量180 kilodaltons和被p-chloromercuriphenylsulfonic酸(p-CMB)迅速灭活。从失活的酶没有保护肌苷(间接宾语),2》-deoxyinosine(恐龙),次黄嘌呤(忧郁),π,或alpha-D-ribose-1-phosphate (Rib-1-P)。孵化不活跃的与二硫苏糖醇还原酶催化活性。反应与p-CMB并不影响粒子的重量。Inosine-guanosine磷酸化酶对热更敏感比嘌呤核苷磷酸化酶失活。半衰期在45摄氏度之间确定pH值5和8 5到9分钟。磷酸(20 mM)稳定热失活的酶,而间接宾语(1毫米),恐龙(1毫米),xanthosine (Xao)(1毫米),Rib-1-P(2毫米),或忧郁(0.05毫米)没有影响。然而,忧郁在1毫米并稳定的酶。此外,π(20毫米)和忧郁的结合(0.05毫米)稳定这种酶在更大程度上比单独π。明显的激活能量11.5千卡/摩尔和7.9千卡/摩尔测定phosphorolytic和合成方向,分别。 The pH dependence of Ino cleavage or synthesis did not vary between 6 and 8. The substrate specificity, listed in decreasing order of efficiency (V/Km), was: 2'-deoxyguanosine, dIno, guanosine, Xao, Ino, 5'-dIno, and 2',3'-dideoxyinosine. Inosine-guanosine phosphorylase differed from the deo operon-encoded purine nucleoside phosphorylase in that neither adenosine, 2'-deoxyadenosine, nor hypoxanthine arabinoside were substrates or potent inhibitors. Moreover, the E. coli inosine-guanosine phosphorylase was antigenically distinct from the purine nucleoside phosphorylase since it did not react with any of 14 monoclonal antisera or a polyvalent antiserum raised against deo-encoded purine nucleoside phosphorylase.