Table 1.

Kinetic parameters of WT Clr4 and the A454R mutant obtained by steady-state methylation experiments conducted at variable peptide concentrations using radioactively labeled AdoMet as a cofactor. K_i-values refer to the inhibition of automethylation by increasing concentrations of H3K9 peptide substrates. All data are given as mean ± SEM. The data and fits are shown in Figure 3 and Figure 5. Reaction conditions were c_enzyme = 0.3 µM, c_peptide = 0–400 µM, c_AdoMet = 0.76 µM. K_m refers to peptide binding at the specified AdoMet concentration. v_max values are given relative to WT activity with 400 µM H3K9me1 peptide.

Substrate	Clr4 WT			Clr4 A454R
	Km (µM)	rel. vmax	Ki (µM)	Km (µM)	rel. vmax	Ki (µM)
H3K9me0	118.9 ± 9.4	1.13 ± 0.18	126.8 ± 7.9	37.2 ± 9.1	0.8 ± 0.05	43.3 ± 0.6
H3K9me1	16.38 ± 2.2	1.05 ± 0.02	24.6 ± 1.82	5.5 ± 1.6	1.14 ± 0.03	11.5 ± 1.6