Aminoacyl-tRNA synthetases from Bacillus stearothermophilus. Asymmetry of substrate binding to tyrosyl-tRNA synthetase.
Aminoacyl-tRNA synthetases from Bacillus stearothermophilus. Asymmetry of substrate binding to tyrosyl-tRNA synthetase.
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来自嗜热脂肪芽孢杆菌的氨酰基-tRNA 合成酶。
DOI：
10.1111/j.1432-1033.1975.tb04091.x
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发表时间：
1975
期刊：
影响因子：
--
通讯作者：
B. Hartley
中科院分区：
文献类型：
--
作者：
H. Bosshard;L. E. Koch;B. Hartley
采用平衡透析、凝胶过滤和荧光光谱等方法研究了L酪氨酸、L酪氨酸二烯酸酯和tRNA-Tyr与嗜热脂肪芽孢杆菌酪氨酰-tRNA合成酶的相互作用。该酶由两个相同的亚基(摩尔比)组成。WT 2 x 44000)，在pH 7.8和23℃时，每个二聚体只与一个L酪氨酸分子结合，K-d为2×10-5M。通过凝胶过滤分离的酪氨酰-tRNA合成酶--酪氨酸二烯酸酯复合体，每个二聚体分子上也有一个腺苷酸结合。相反，每个酶二聚体都有两个tRNA-Tyr分子结合，但这两个结合部位在pH 6.5和25℃时的K-d值分别为2×10-7M和1.3×10-6M。由于对游离酶[2]的结晶学分析表明，单体是不对称单位，数据表明底物结合导致了酶的不对称。
The interaction of L-tyrosine, L-tyrosyladenylate and tRNA-Tyr with tyrosyl-tRNA synthetase from Bacillus stearothermophilus was studied by equilibrium dialysis, gel filtration and fluorescence spectroscopy. The enzyme, which consists of two identical subunits (mol. wt 2 x 44000), binds only a single molecule of L-tyrosine per dimer with a K-d of 2 x 10-5 M at pH 7.8 and 23 degrees C. The tyrosyl-tRNA synthetase--tyrosyladenylate complex which was isolated by gel filtration also has one adenylate bound per dimeric enzyme molecule. In contrast, two tRNA-Tyr molecules bind per enzyme dimer, but the two binding sites are not equivalent having K-d values of 2 x 10-7 M and 1.3 x 10-6 M respectively at pH 6.5 and 25 degrees C. Since crystallographic analysis of the free enzyme [2] shows that the monomer is the asymmetric unit, the data indicate that substrate binding induces asymmetry in the enzyme.