. 2005 Jun;71(6):3285–3293. doi: 10.1128/AEM.71.6.3285-3293.2005

TABLE 1.

Apparent kinetic constants of glucose dehydrogenases harboring E170K, Q252L, and E170K/Q252L substitutions^a

Enzyme	Apparent K_m (Glu) (mM)	Apparent K_m (NAD⁺) (mM)	Apparent K_m (NADP⁺) (mM)	Apparent k_cat (Glu) (s⁻¹)	Apparent k_cat (Glu)/apparent K_m (Glu) (mM⁻¹ s⁻¹)
Wild type	14	0.17	0.033	395	28
Q252L	8	0.15	0.043	317	40
E170K	7.5	0.22	0.051	352	47
Q252L/E170K	8.5	0.33	0.049	334	39

Apparent kinetic constants were determined as described previously (1). The enzyme activity was measured with a Beckman DU-7500 spectrophotometer equipped with a thermostatic circulating water bath. The d-glucose concentrations for K_m determinations were varied from 0.1 mM to 20 mM in 50 mM Tris-HCl buffer (pH 8.0) containing 0.5 mM NAD⁺, while the K_m values for NAD⁺ and NADP⁺ were determined with 0.15 to 2.0 mM NAD⁺ and 0.05 to 2 mM NADP in 50 mM Tris-HCl buffer (pH 8.0) containing 0.1 M glucose.