TABLE 3.
Metal content, EDTA inhibition, and apparent affinities and activities with divalent cations of cPGIs from P. furiosus, A. fulgidus, M. mazei, S. enterica serovar Typhimurium, and E. melilotia
| Parameter | Propertyb of:
|
||||
|---|---|---|---|---|---|
| PfPGI* | AfcPGI* | MmcPGI | StcPGI | EmcPGIA | |
| Assay temp (°C) used | 80 | 50 | 37 | 37 | 50 |
| Metal content (mol/mol subunit) | |||||
| Ni2+ | 0.39*/0.12† | 0.41‡/0.06* | - | 0.20 | 0.07 |
| Fe2+ | 0.04*/0.07† | 0.03‡/0.01* | - | 0.17 | 0.13 |
| Ki EDTA (mM) | 55 | 97 | 101 | 120 | 210 |
| Metal reactivation apparent affinities Kaff (μM) | |||||
| Ni2+ | 7 | 37 | 1,180 | 22 | ND |
| Fe2+ | 40 | 7 | 200 | 50 | ND |
| Mn2+ | 61 | 81 | 220 | 38 | ND |
| Zn2+ | 17c | 46 | 130 | 22 | ND |
| Apparent Vmax (U/mg) | |||||
| Ni2+ | 61 | 7.0 | 2.3 | 1.2 | ND |
| Fe2+ | 92 | 2.8 | 2.3 | 0.5 | ND |
| Mn2+ | 26 | 6.2 | 2.3 | 1.2 | ND |
| Zn2+ | 51 | 1.8 | 1.3 | 0.7 | ND |
| Velocity at a 100 μM concn of metal | |||||
| Co2+ | 44 | 2.2 | 1.2 | ||
| Cd2+ | 23 | 2.1 | 0.4 | ND | |
| Ca2+ | 33 | 0.1 | 0.03 | ND | |
| Cu2+ | 0.5 | ND | - | 0.02 | ND |
| Mg2+ | 28 | 0.01 | - | 0.02 | ND |
a
The metal content was measured by atomic absorption spectroscopy. Apparent KMe,0.5V values and apparent Vmax values (substrate fructose-6-phosphate) were derived from reactivation curves of cPGIs (Fig. 2). All metals were used in the form of chlorides.
b
*, Recombinant protein without His tag; †, purified from P. furiosus; ‡, recombinant protein with His tag; ND, not detectable; -, not measured.