Table 4.

Single-turnover rate constants for deacylation of tRNA^Pro acceptor-stem mutants mischarged with alanine by MCP3 and FL ProRS.

Ala-tRNAPro Acceptor Stem Mutant	MCP3 kobs (sec−1)*	Fold-change†	FL ProRS kobs (sec−1)*	Fold-change†
WT	0.198 ± 0.068	–	0.069 ± 0.010	–
C73A	0.007 ± 0.006	28	0.002 ± 0.0002	35
G1:C72G	0.127 ± 0.015	1.5	0.032 ± 0.009	2.2
G1:C72G, C73A	0.031 ± 0.008	6.4	0.002 ± 0.0003	35

*k_obs values determined using 500 nM enzyme and 50 nM Ala-tRNA^Pro at 27°C. Standard deviations represent the average of three independent trials. †Fold-change is based on the WT Ala-tRNA^Pro deacylation.