On the Interaction of Seryl‐tRNA Synthetase with tRNASer
On the Interaction of Seryl‐tRNA Synthetase with tRNASer
复制标题
Seryl-tRNA 合成酶与 tRNASer 的相互作用
DOI：
--
复制
发表时间：
1976
期刊：
影响因子：
--
通讯作者：
H. Zachau
中科院分区：
文献类型：
--
作者：
R. Rigler;U. Pachmann;R. Hirsch;H. Zachau
通过跟踪酵母丝氨酰-tRNA合成酶在添加tRNASer时的色氨酸荧光，观察到tRNA结合位点的数目随温度、ATP或KCl浓度的增加而从两个减少到一个。同时观察到表观结合常数显著降低。结合位点数目的变化可通过存在至少一个温度和离子强度敏感性结合位点和一个温度和离子强度独立性结合位点来解释。
弛豫动力学实验揭示了两个结合过程：一个快速的依赖于tRNA浓度和离子强度和一个缓慢的，这似乎是独立的tRNA浓度和离子强度。酶动力学研究表明，丝氨酰-tRNA合成酶的活性强烈依赖于KCl浓度，并在0.2 M KCl时表现出最大值。基于弛豫和酶动力学实验的数据，提出了涉及第一非特异性步骤的识别过程的模型，其中所有的tRNA，同源和非同源。与合成酶结合（扫描步骤）。然后通过tRNA合成酶复合物的构象转变在识别位点进行同源tRNA的鉴定（鉴定步骤）
By following the tryptophan fluorescence of yeast seryl-tRNA synthetase on additition of tRNASer it was observed that the number of binding sites for tRNA decreases from two to one with increasing temperature, ATP or KCl concentration. Concomitantly a considerable decrease of the apparent binding constant was observed. The variation in the number of binding sites is explained by the presence of at least one temperature and ionic strength sensitive binding site and one temperature and ionic strength independent binding site.
Relaxation kinetic experiments revealed two binding processes: a fast one depending on tRNA concentration and ionic strength and a slow one, which appeared to be independent of tRNA concentration and ionic strength. Enzyme kinetic studies showed that the activity of seryl-tRNA synthetase strongly depends on the KCI concentration and exhibits a maximum at 0.2 M KCl. Based on the data from relaxation and enzyme kinetic experiments a model is suggested for the recognition process involving a first unspecific step where all tRNAs, cognate and non-cognate. are bound to the synthetase (scanning step). The identification of the cognate tRNA is then performed at-the recognition site by a conformational transition of the tRNA synthetase complex (identification step)