TABLE 2.
Biochemical and kinetic properties of ATP-GLK from A. pernixa
| Parameter | Result for enzyme from:
|
|
|---|---|---|
| A. pernix | E. coli (recombinant) APE2091 | |
| Apparent mol mass of enzyme (kDa) | ||
| Native | 30-33 | 30-33 |
| Subunit | 36 | 41 |
| Calculated | 33.843 | 42.119b |
| Oligomeric structure | α | α |
| pH optimum | 6.2 | 6.2 |
| Temp optimum (°C) | >100 | >100 |
| Arrhenius activation energy (kJ mol−1) | 66 | NDd |
| Apparent Km (mM) with ATP | 0.42 | 0.47 |
| Phosphoryl donor specificity (%)c | ||
| ATP | 100 | 100 |
| ITP | 40 | 41 |
| GTP | 9 | 7 |
| UTP | 3 | ND |
| CTP | 0 | ND |
| ADP | 0 | 0 |
| GDP | 0 | 0 |
| UDP | 0 | 0 |
| Acetyl phosphate | 0 | 0 |
| PPi | 1 | 1 |
| Cation specificity (% at 90°C)c | ||
| Mg2+ | 100 | ND |
| Co2+ | 83 | ND |
| Mn2+ | 64 | ND |
| Ni2+ | 23 | ND |
| Cu2+ | 6 | ND |
a
The molecular mass of native enzyme was determined by gel filtration of subunits by SDS-PAGE Enzyme activity was measured at 90°C in the direction of G6P formation in a discontinuous assay with GPD.
b
This value includes the 16 amino acids of the leader peptide.
c
The direction of G6P formation is represented as the percentage of Vmax, where 100% = 35 U/mg. Each value represents the specific substrate shown.
d
ND, not determined.