Coleman D E, Carter C W
Biochemistry. 1984 Jan 17;23(2):381-5. doi: 10.1021/bi00297a030.
It has previously been shown that tryptophanyl-tRNA synthetase from Bacillus stearothermophilus crystallizes in different forms, depending on the substrates present during crystallization [Carter, C. W., Jr., & Carter, C. W. (1979) J. Biol. Chem. 254, 12219-12223]. Radiolabeling experiments show that the tetragonal crystals (type IV), grown in the presence of tryptophan and ATP, contain enzymatically formed 3'(2')-tryptophanyladenosine 5'-triphosphate (Trp-ATP). Trp-ATP is formed by acyl transfer of the tryptophanyl moiety of an acyladenylate intermediate, Trp-5'-AMP, to a second molecule of ATP bound in the site normally occupied by the 3' CCA terminus of tRNATrp. This compound is therefore a chemical marker in type IV crystals for that part of the tRNA binding site on the synthetase. Solution of this crystal structure, now in progress, may therefore provide useful information concerning the mechanism of aminoacylation of tRNATrp by this enzyme and may help locate its tRNA binding site.
此前已经表明，嗜热脂肪芽孢杆菌的色氨酰 - tRNA合成酶会以不同形式结晶，这取决于结晶过程中存在的底物[卡特，小C.W.，&卡特，C.W.（1979年）《生物化学杂志》254卷，12219 - 12223页]。放射性标记实验表明，在色氨酸和ATP存在的情况下生长的四方晶体（IV型）含有酶促形成的3'（2'） - 色氨酰腺苷5'-三磷酸（Trp - ATP）。Trp - ATP是由酰基腺苷酸中间体Trp - 5'-AMP的色氨酰部分的酰基转移至结合在通常由tRNATrp的3' CCA末端占据的位点上的第二个ATP分子形成的。因此，该化合物是IV型晶体中合成酶上tRNA结合位点那部分的化学标记。目前正在解析该晶体结构，这可能会提供有关该酶对tRNATrp进行氨酰化作用机制的有用信息，并可能有助于确定其tRNA结合位点。
