Table 1.

The Michaelis–Menten parameters for peptide release by the methylated and unmethylated RFs on cognate and near-cognate codons

Codon	A site codon	Release factor	kcat (s−1)	KM (μM−1)	kcat/KM (s−1 μM−1)
Cognate	UAA	mRF2	10.4 ± 0.04	0.49 ± 0.007	21.2 ± 0.40
		RF2	6.0 ± 0.17	0.30 ± 0.01	20.0 ± 0.008
	UGA	mRF2	10.7 ± 0.03	0.38 ± 0.009	28.2 ± 0.36
		RF2	6.8 ± 0.19	0.28 ± 0.04	24.3 ± 0.007
Near-cognate	UAG	mRF2	0.13 ± 0.01	15.5 ± 1.76	0.008 ± 0.0006
		RF2	0.28 ± 0.004	14.7 ± 0.10	0.019 ± 0.0004
	UGG	mRF2	0.10 ± 0.04	22 ± 1.4	0.0045 ± 0.0001
		RF2	0.25 ± 0.03	14.4 ± 0.11	0.017 ± 0.0006
Cognate	UAA	mRF1	8.3 ± 0.06	0.06 ± 0.005	138.3 ± 0.003
		RF1	2.0 ± 0.04	0.03 ± 0.03	66.7 ± 0.005
Near-cognate	UGA	mRF1	0.16 ± 0.004	2.7 ± 0.03	0.059 ± 0.004
		RF1	0.12 ± 0.003	2.6 ± 0.26	0.046 ± 0.004

The values are obtained from M-M plots (Figs. 2 and 3, right panels) with SEM (Standard Error of Mean) estimated from at least three independent sets of experiments.