TABLE 2.
Steady-state kinetic parameters
Average values ± S.E. (n = 3) are shown. Assays were performed in the presence of either 5 mm DTT (RED, reduced) or 5 mm trans-4,5-dihydroxy-1,2-dithiane (OX, oxidized), as indicated.
| kcat | bKmAPS | KiAPS | kcat/KmAPS | KmATP | bkcat/KmATP | |
|---|---|---|---|---|---|---|
| s−1 | μm | μm | m−1 s−1 × 106 | μm | m−1 s−1 × 106 | |
| SynAPSKRED | 28.1 ± 1.6 | 0.30 ± 0.05 | 14.7 ± 2.4 | 93.67 | 0.16 ± 0.07 | 175.6 |
| SynAPSKOX | 19.3 ± 0.5 | 0.23 ± 0.02 | 18.2 ± 2.1 | 83.91 | 0.13 ± 0.06 | 148.5 |
| T61ERED | 23.5 ± 0.8 | 0.28 ± 0.03 | 19.5 ± 2.6 | 83.93 | 0.20 ± 0.08 | 117.5 |
| H23CRED | 19.0 ± 0.9 | 0.22 ± 0.03 | 12.8 ± 1.7 | 86.36 | 0.15 ± 0.05 | 126.7 |
| H23COX | 17.6 ± 1.1 | 0.20 ± 0.05 | 16.6 ± 3.2 | 88.00 | 0.16 ± 0.08 | 110.0 |
| SynAPSKfusRED | 26.3 ± 1.3 | 0.32 ± 0.05 | 14.8 ± 2.0 | 82.19 | 0.27 ± 0.11 | 97.41 |
| SynAPSKfusOX | 18.7 ± 1.1 | 0.24 ± 0.06 | 12.0 ± 2.4 | 77.92 | 0.19 ± 0.04 | 98.42 |
| SynAPSKfus/H23CRED | 11.0 ± 0.5 | 0.11 ± 0.02 | 20.4 ± 3.1 | 100.0 | 0.15 ± 0.06 | 73.33 |
| SynAPSKfus/H23COX | 12.8 ± 1.1 | 0.49 ± 0.09 | 2.6 ± 0.4 | 26.12 | 0.28 ± 0.04 | 45.71 |
| AtAPSKREDa | 272 ± 39 | 0.48 ± 0.41 | 37.5 ± 6.9 | 567 | 0.18 ± 0.09 | 1,511 |
| AtAPSKOXa | 14.1 ± 2.3 | 0.43 ± 0.26 | 2.5 ± 0.8 | 0.328 | 0.21 ± 0.04 | 67.1 |
a Values for AtAPSK were reported previously (8) and are included here for comparison.