. 2006 Aug 11;34(13):3811–3818. doi: 10.1093/nar/gkl517

Table 2.

Dissociation constants and observed rate constants for T.maritima tRNase Z variants

Enzyme	Ion	Pre-tRNA^Arg (₇₄CCA₇₆)
		Cleavage	K_d (μM)^a	k_obs (min⁻¹)^b
D52S	Mg²⁺	—	0.35 ± 0.083	—
	Mn²⁺	—	0.29 ± 0.018	—
D52E	Mg²⁺	—	0.29 ± 0.160	—
	Mn²⁺	CC\|A	ND	0.36 ± 0.004
H222C	Mg²⁺	—	0.39 ± 0.095	—
	Mn²⁺	CCA\|	ND	< 0.01
H222S	Mg²⁺	—	0.36 ± 0.094	—
	Mn²⁺	—	0.25 ± 0.087	—
H222K	Mg²⁺	—	0.23 ± 0.020	—
	Mn²⁺	CCA\|	ND	0.06 ± 0.003

|, primary cleavage site; ND, not determined; —, cleavage not detected or hardly detected (Supplementary Figure 1).

^aData are the means ± SD of three independent experiments (Supplementary Figure 2).

^bEach fluorescein-labeled pre-tRNA (20 nM) was reacted with each variant (700 nM) at 60°C for 3 min. Data are the means ± SD of three independent experiments.