Blechschmidt B, Jahn W, Hainfeld J F, Sprinzl M, Boublik M
Laboratorium für Biochemie, Universität Bayreuth, Germany.
J Struct Biol. 1993 Jan-Feb;110(1):84-9. doi: 10.1006/jsbi.1993.1007.
Scanning transmission electron microscopy (STEM) was used to visualize formation of a ternary complex between the T. thermophilus elongation factor (EF) Tu.GTP and the Escherichia coli Phe-tRNA(Phe) labeled with an undecagold (Au11) cluster at minor nucleotide 3-(3-amino-3-carboxypropyl) uridine at position 47. The ternary complex was further characterized by the molecular mass and radius of gyration calculated from the mass distribution within the individual particles. Under conditions used for STEM imaging, the ternary complex is formed between Au11-labeled Phe-tRNA(Phe) and Tu.GTP in a yield up to 25%. The stoichiometry of EF-Tu.GTP to aminoacyl-tRNA (aa-tRNA) in the EF-Tu.GTP.aa-tRNA complex is 1:1, in agreement with the established view of the protein biosynthesis mechanism. The ternary complex is also formed, although to a lower extent, with GTP analogues (GMPPCP and GMPPNP, respectively), but not with Tu.GDP and nonaminoacylated tRNA(Phe) with Tu.GTP.
扫描透射电子显微镜（STEM）用于观察嗜热栖热菌延伸因子（EF）Tu·GTP与在第47位的次要核苷酸3-(3-氨基-3-羧丙基)尿苷处用十一金（Au11）簇标记的大肠杆菌苯丙氨酰-tRNA（Phe-tRNA(Phe)）之间三元复合物的形成。通过从单个颗粒内的质量分布计算出的分子量和回转半径对三元复合物进行进一步表征。在用于STEM成像的条件下，Au11标记的Phe-tRNA(Phe)与Tu·GTP之间形成三元复合物，产率高达25%。EF-Tu·GTP·aa-tRNA复合物中EF-Tu·GTP与氨酰-tRNA（aa-tRNA）的化学计量比为1:1，这与已确立的蛋白质生物合成机制观点一致。三元复合物也能与GTP类似物（分别为GMPPCP和GMPPNP）形成，尽管程度较低，但不能与Tu·GDP以及Tu·GTP存在时的非氨酰化tRNA(Phe)形成。
