Smith S L, Douglas K T
Department of Pharmacy, University of Manchester, U.K.
Biochem Biophys Res Commun. 1989 Jul 31;162(2):715-23. doi: 10.1016/0006-291x(89)92369-3.
Using ribonucleotide reductase (EC 1.17.4.1) purified from E. coli clones with overproducing plasmids for the B1 and B2 subunits, respectively, studies have been carried out of the inhibition of this enzyme by cisplatin. Under anaerobic conditions, using the dithiol, reduced form of the enzyme, it was found that ribonucleotide reductase is extremely sensitive to cisplatin: greater than 90% inhibition was achieved with 2-fold molar excess of platinum reagent even at 10(-8)M enzyme. Inhibition was essentially instantaneous and irreversible to G-25 gel filtration. The site of inhibition was found to be the B1 subunit. Transplatin was much less effective. Inhibition of the enzyme by cisplatin (molar ratio cisplatin:B1 = 4.3) led to a decrease in thiol titre corresponding to approximately 1 thiol group per dimer of B1 subunits under conditions leading to 94% inactivation of the ribonucleotide reductase activity.
分别使用从带有B1和B2亚基过量表达质粒的大肠杆菌克隆中纯化得到的核糖核苷酸还原酶（EC 1.17.4.1），开展了顺铂对该酶抑制作用的研究。在厌氧条件下，使用二硫醇、酶的还原形式，发现核糖核苷酸还原酶对顺铂极其敏感：即使在酶浓度为10⁻⁸M时，铂试剂摩尔过量两倍就能实现超过90%的抑制率。抑制作用基本上是瞬间发生的，并且对G-25凝胶过滤不可逆。发现抑制位点是B1亚基。反铂的效果要差得多。在导致核糖核苷酸还原酶活性94%失活的条件下，顺铂对该酶的抑制作用（顺铂与B1的摩尔比为4.3）导致硫醇滴定度下降，相当于每个B1亚基二聚体约1个硫醇基团。
