Figure 2.

Stopped-flow-based fluorescent BOP-Met-Leu-Leu tripeptide release kinetics by mRF2 and RF2 on RCs containing cognate/near-cognate codons. The left (A, D, G, and J) and the middle panels (B, E, H, and K) present the time courses of BOP fluorescence change in arbitrary units (a.u.) due to BOP-Met-Leu-Leu tripeptide release from cognate RC_UAA and RC_UGA and near-cognate RC_UAG and RC_UGG (0.1 μM), with increasing concentrations of mRF2 (left) and RF2 (middle). The right panels (C, F, I, and L) represent the Michaelis–Menten plots (M-M plot) demonstrating dependence of the observed peptide release rates (derived from the titration curves in the left and middle panels), on the concentration of mRF2 and RF2 on corresponding codons (labeled in the left for each row). The kinetic parameters (k_cat, K_M, and k_cat/K_M) are derived by fitting the curves with hyperbolic function. The error bars indicate SEM from minimum three sets of independent experiments.