A tRNA body with high affinity for EF-Tu hastens ribosomal incorporation of unnatural amino acids

Dependence of the rate of fast phase of dipeptide synthesis on ribosome concentration in the reaction mixture. The normalized time course of f[³H]Met-mS (A) or f[³H]Met-bK (B) dipeptide formation for different concentrations of preinitiated ribosomes with the Ala codon (GCA) in the A site (see Materials and Methods). (C) The average times of dipeptide formation τ_dip, estimated from the experiments in A (□) and B (▪), were plotted versus the inverse of ribosome concentration (Lineweaver-Burke plot); τ_dip^min- values for dipeptide formation, which is equal to the y-intercept, were estimated from the fits as 13.8 ± 3.7 msec for mS-tRNA^AlaB (□) and 13.3 ± 2.3 msec for bK-tRNA^AlaB (▪).