Table 2.

Stability of Glu-tRNA^Gln and Gln-tRNA^Gln

	Half-life (min)
	Glu-tRNAGln	Gln-tRNAGln
No enzyme	54 ± 1	57 ± 3
GatCAB	245 ± 43	444 ± 111
GluRS2	26 ± 3	26 ± 2
GluRS2 + GatCAB	50 ± 1	55 ± 6

Half-lives for both aa-tRNAs were measured by incubating purified Glu-tRNA^Gln or Gln-tRNA^Gln in the standard reaction mixture for transamidation, from which Gln and ATP were excluded, at 37°C. When added, proteins were at a concentration of 20 µM. GatCAB protected the ester bond of both aa-tRNAs, while GluRS2 showed a deacylating activity.