TABLE 3.

Steady-state deacylation by IleRS and ValRS

The values represent the mean ± S.D. of at least three independent experiments.

	kobs
	s−1
IleRS + Val-tRNAIle
WT IleRSa	0.22 ± 0.04
IleRS T243Ra	0.093 ± 0.004
IleRS D342Ab	0.009 ± 0.003
IleRS T243R/D342Ab	c
ValRS + Thr-tRNAVal
WT ValRSd	6.4 ± 0.09
ValRS K277Pb	c
ValRS D286Ab	c
ValRS K277P/D286Ab	c

^a WT IleRS and the IleRS T243R mutant were each present at 100 nm concentration.

^b IleRS D342A and T243R/D342A, and all ValRS mutants, were each present at 1 μm concentration.

^c Activity was too low for reliable detection.

^d WT ValRS was present at 5 nm concentration.