DISSOCIATION OF GUANOSINE NUCLEOTIDE-ELONGATION FACTOR G-RIBOSOME COMPLEXES
DISSOCIATION OF GUANOSINE NUCLEOTIDE-ELONGATION FACTOR G-RIBOSOME COMPLEXES
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DOI：
10.1021/bi00575a029
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发表时间：
1979-01-01
期刊：
影响因子：
2.9
通讯作者：
MODOLELL, J
中科院分区：
文献类型：
--
作者：
CAMPUZANO, S;VAZQUEZ, D;MODOLELL, J
测定了含有[大肠杆菌]延伸因子G （EF-G）、核糖体和GDP加夫西地酸、鸟酰-5”-酰基咪啶二磷酸或鸟酰-5”-酰基亚甲基二膦酸的配合物的自发解离。它遵循两相动力学，可以分解为21阶衰减率。两类配合物可能存在，其表观解离速率常数(k)相差5至20倍。k的值和配合物在快衰类和慢衰类之间的分布取决于解离发生的条件，而不取决于形成配合物的条件。只有当解离发生的化学环境被改变时，配合物才会从一类迅速转变为另一类。增加NH4Cl的浓度或加入抗生素硫链霉素加速衰变，并将缓慢解离转化为快速解离的复合物。添加引起误读的新霉素、卡那霉素、链霉素和庆大霉素（但不包括潮霉素）组的氨基糖苷类抗生素可以减缓腐蚀。10 .mu的新霉素B。M，这种效应是由于快速到缓慢衰变的配合物的转换。提出了一个模型来解释涉及配合物构象转变的结果。
The spontaneous dissociation of complexes containing [Escherichia coli] elongation factor G (EF-G), the ribosome and either GDP plus fusidic acid, guanyl-5''-yl imidodiphosphate or guanyl-5''-yl methylene diphosphonate was measured. It follows biphasic kinetics that can be resolved into 2 1st-order decay rates. Two classes of complexes may exist with apparent dissociation rate constants (k) differing 5 to 20-fold. The values of k and the distribution of complexes between the fast and the slowly decaying class depend on the conditions in which the dissociation occurs but not on the conditions in which the complexes are formed. Rapid transitions of complexes from one to the other class occur only when the chemical environment in which the dissociation takes place is modified. Increasing the concentration of NH4Cl or adding the antibiotic thiostrepton accelerates the decay and converts slowly dissociating into fast dissociating complexes. Addition of misreading-inducing aminoglycoside antibiotics of the neomycin, kanamycin, streptomycin and gentamicin (but not hygromycin) groups slows down the decay. For neomycin B at 10 .mu.M, this effect is due to the conversion of fast into slowly decaying complexes. A model to explain the results involving conformational transitions of the complexes is proposed.