. 2005 Apr 7;33(6):2012–2021. doi: 10.1093/nar/gki344

Table 2.

Summary of cleavage rate constants in cleavage of different substrate variants at pH 6.1 at various Mg²⁺ concentrations

Substrate		40 mM		160 mM	400 mM
		k_obs	k_obs/K^sto	k_obs	k_obs
pATSerUGG/C
	−1	n.d.		n.d.	n.d.
	+1	1.2 ± 0.2^a	3.8 ± 0.6	1.4 ± 0.18	0.46 ± 0.29
pATSerUGU/A
	−1	n.d.		n.d.	n.d.
	+1	0.0077 ± 0.0039	0.11 ± 0.05	0.10 ± 0.023	0.20 ± 0.10
	+2	n.d.		n.d.	n.d.
pATSerUGU/DAP
	−1	n.d.		n.d.	n.d.
	+1	0.0005 ± 0.00005	0.015 ± 0.004	0.016 ± 0.002	0.032 ± 0.010
	+2	n.d.		n.d.	n.d.
pATSerCGG/C
	−1			0.055 ± 0.0061	0.065 ± 0.0081
	+1	n.d.	n.d.	0.19 ± 0.026	0.15 ± 0.055
pATSerCGU/A
	−1				0.013 ± 0.001^a
	+1	n.d.	n.d.	n.d.	0.016 ± 0.002^a
pATSerCGU/DAP
	−1			0.015 ± 0.001^a	0.0083 ± 0.0015
	+1	n.d.	n.d.	0.041 ± 0.002^a	0.045 ± 0.004
pGlnU/A
	−1	n.d.	n.d.
	+1	0.47 ± 0.12	0.20 ± 0.10	n.d.	n.d.
	+2	n.d.	n.d.
pGlnG/C
	−1	n.d.	n.d.
	+1	2.8 ± 0.50	9.4 ± 1.4	n.d.	n.d.
	+2	n.d.	n.d.
pSu3G/C
	+1	2.5 ± 0.77	4.3 ± 1.2	n.d.	n.d.
pSu3U/A
	+1	0.012 ± 0.0035	0.053 ± 0.027	n.d.	n.d.

The experiments were performed as described in Materials and Methods. Each value is an average of several independent experiments and n.d. = not determined while −1, +1 and +2 refers to the cleavage site. k_obs and k_obs/K^sto (= k_cat/K_m) are expressed as min⁻¹ and min⁻¹ × μM⁻¹, respectively.

^aBased on two independent determinations. Underlined residues correspond to the identity of the +1/+72 base pair. The finding that the rates of cleavage for pATSerUGG/C, pATSerUGU/A and pATSerUGU/DAP were linear dependent on [OH⁻] up to at least pH 6.5 suggested that the rate of cleavage at pH 6.1 is rate limiting (data not shown).