Interaction of elongation factor EF-Tu with gamma-amides of GTP and beta-amides of GDP bearing the azidoaryl group or the chloroethylaminoaryl group placed at the terminal phosphate.

New types of azidoaryl analogs of GTP: gamma-(4-azido)anilide of GTP (I), gamma-(n-(4-azidobenzyl)-N-methyl)amide of GTP (II) and of GDP: beta-(4-azido)anilide of GDP (III), beta-(N-(4-azidobenzyl)-N-methyl)amide of GDP (IV) have been synthesized by treatment of the nucleotide in aqueous solution with N-cyclohexyl-N-beta-(4-methylmorpholinium)-ethylcarbodiimide p-toluene sulfonate and the respective amine. The analog of GTP bearing at the gamma-phosphate an alkylating 2-chloroethylamino group: gamma-(4-N-(2-chloroethyl)-N-methylaminobenzyl)amide of GTP (V) was prepared by the method described previously for the preparation of the analog of ATP (Knorre, D.G., Kurbatov, V.A. and Samukov, V.V. (1976) FEBS Lett. 70, 105-108). Azidoaryl analogs of GTP and GDP as well as the chloroethylaminoaryl analog of GTP compete with GDP in the formation of the binary complex EF-Tu.GDP with the respective Ki values 3.9.10(-7) M (I), 2.9.10(-8)M (II), 6.9.10(-7)M (III), 5.0.10(-7)M (IV) and 3.8.10(-8)M (V) relative to GDP. The dissociation constants of the complexes of the radioactively-labeled GTP analogs I, II and V with elongation factor Tu were calculated to be 8.5.10(-6)M, 3.4.10(-7)M and 4.6.10(-8)M, respectively, or approx. 1740-, 70- and 9-times greater than that of GDP. GTP analogs I, II and V were found to substitute GTP in the stimulation of EF-Tu-dependent binding of aminoacyl-tRNA to the ribosome-mRNA complex.