. Author manuscript; available in PMC: 2011 Apr 27.

Published in final edited form as: Biochemistry. 2010 Apr 27;49(16):3436–3444. doi: 10.1021/bi9022297

Table 2.

Kinetic characterization of SMP30 with gluconolactone and its metal dependence ^a

	K_M (mM) ^a	k_cat (s⁻¹) ^a	k_cat/K_M (mM⁻¹s⁻¹) ^a	K_d (µM) ^b	Cellular concentrations ^c
Zn²⁺	2.7 ± 0.5	341 ± 35	126 ± 27	7.0 ± 0.9	fM-nM
Mn²⁺	0.6 ± 0.1	79 ± 8	132 ± 26	0.6 ± 0.1	0.1–10 µM
Mg²⁺	1.3 ± 0.3	31 ± 4	24 ± 7	82 ± 21	500 µM
Ca²⁺	3.7 ± 0.7	48 ± 6	13 ± 3	566 ± 249	0.1–1 µM (resting)/ 1000 µM (stress)

K_M and k_cat values are reported for human SMP30 using the substrate gluconolactone and a saturating concentration of the divalent metal ion listed using conditions detailed in the materials and methods.

The reported K_d values were obtained using 10 mM gluconolactone and varying the metal concentration to obtain velocities. A fit of Equation 1 to data shown in Figure 4 yielded the reported values of K_d as detailed in material and methods.

Estimates of physiological concentration of divalent cations were taken from the litterature (34–40).