Table 2. Activity of 17E/DS under single turnover conditions with 100 µM M²⁺ at pH 7.0 or with 10 mM M²⁺ at pH 6.0.

Cofactor	kobs (min–1)		pKa (59)
	100 µM, pH 7	10 mM, pH 6
Ba2+	–	0.0003	13.82
Sr2+	0.0058	0.0005	13.18
Mg2+	0.011	0.017	11.42
Ca2+	0.012	0.015	12.7
Ni2+	0.029	0.008	9.86
Cd2+	0.095	–	10.08
Co2+	0.20	0.25	9.65
Mn2+	0.28	0.24	10.6
Zn2+	1.7	1.35	8.96