Table 2. Specific activity and kinetic constants of various light chain constructs.
| LC variant | Sp. Act. (µmol/min/mg) | Rel. Sp. Act. | Km (mM) | kcat (Sec−1) | Rel. kcat | kcat/Km |
| LC | 2.15±0.01 | 100 | 3.36 | 9.00 | 100 | 2.68 |
| LC+Belt | 0.27±0.02 | 15.0 | 1.30 | 0.31 | 3.4 | 0.24 |
| LC+Hn' | 0.09±0.001 | 8.2 | n.d. | n.d. | - | - |
| LC+Hn | 0.02±0.00 | 1.6 | 0.8 | 0.09 | 1.0 | 0.11 |
| BoNT/A | 0.09±0.01 | 12 | 4.29 | 1.42 | 15.8 | 0.33 |
Specific activity (Sp. Act.) was determined at a fixed substrate concentration of 0.9 mM in triplicate. Km and kcat values were calculated from double reciprocal plots shown in Figure 7.