. Author manuscript; available in PMC: 2010 Mar 1.

Published in final edited form as: Protein Expr Purif. 2008 Oct 19;64(1):82–88. doi: 10.1016/j.pep.2008.10.005

Table 2.

Table 2a. Enzymatic properties of the PDE8A1 catalytic domain for cAMP as substrate
PDE8A	Metal ion	K_M (μM)	k_cat (s⁻¹)	Vmax (μmol/mg/min)	k_cat/K_M (s⁻¹ μM⁻¹)
8ACATref	10 mM Mg²⁺	7.0 ± 0.1	2.9 ± 0.1	4.5 ± 0.1	0.4 ± 0.1
8ACATref	4 mM Mn²⁺	1.8 ± 0.1	4.0 ± 0.1	6.1 ± 0.1	2.2 ± 0.1
8A205ref	4 mM Mn²⁺	0.28± 0.01	1.1 ± 0.1	0.93 ± 0.04	3.9 ± 0.1
8ACATnat	10 mM Mg²⁺	1.0 ± 0.1
8ACATnat	4 mM Mn²⁺	1.5 ± 0.2

Table 2b. Enzymatic properties of the PDE8A1 catalytic domain for cGMP as substrate
PDE8A	Metal ion	K_M (mM)	k_cat (s⁻¹)	Vmax (μmol/mg/min)	k_cat/K_M (s⁻¹ μM⁻¹)
8ACATref	10 mM Mg²⁺	1.5 ± 0.2	0.4 ± 0.1	0.6 ± 0.1	0.3 ± 0.1 × 10⁻³
8ACATref	4 mM Mn²⁺	1.6 ± 0.1	1.6 ± 0.2	2.5 ± 0.3	1.0 ± 0.1 × 10⁻³

8ACATref and 8ACATnat represent the catalytic domains of PDE8A (residues 480–820) respectively from the refolding and natural folding in E. coli.

8A205ref is the PDE8A fragment with residues 205–820 from the refolding.