Fig. 1.

Aminoacylation of tRNA^Phe with cognate and noncognate amino acids and specific deacylation of mischarged product. (A) Aminoacylation of E. coli tRNA^Phe transcript (1.2 μM) with Phe or m-Tyr by HsmtPheRS (210 nM) or TtPheRS (24 nM) analyzed by electrophoresis in 8% denaturing gel at acidic conditions (0.1 M Na-acetate, pH 5). (B) Specific deacylation of m-Tyr-tRNA^Phe. E. coli tRNA^Phe transcript (1.2 μM) was aminoacylated with Phe (25 μM), m-Tyr (125 μM), or Tyr (1 mM) by HsmtPheRS (250 nM in experiments with Phe and m-Tyr, or 500 nM in experiments with Tyr) for 5 min; then the reaction was continued after addition (shown by arrows) of TtPheRS (16 nM), EcPheRS (48 nM), or HsctPheRS (32 nM).