Table 1. Calculated values of the rate and dissociation constants from Scheme 4.
Rate and dissociation constants for CoBcII-catalysed hydrolysis of cefoxitin (1), cephaloridine (2) and benzylpenicillin (3) in 0.025 M buffer, I=0.25 M, at 30 °C, (Kd=6.0×10−5 M). The corresponding values, determined in similar conditions for the native ZnBcII, are given for comparison.
| kcat/Km (106 M−1·s−1) | kcat (s−1) | Km (10−6 M) | pKa | Km1 (10−6 M) | Km2 (10−6 M) | ||
|---|---|---|---|---|---|---|---|
| 1 | Co2+ | 0.052±0.009 | 16±2.0 | 310±10 | 6.52±0.1 | 12±1.0 | 100±20 |
| Zn2+ | 0.00027±0.00005 | 0.57±0.1 | 2100±200 | ||||
| 2 | Co2+ | 1.7±0.3 | 67±10 | 40±10 | 6.52±0.1 | 3.0±0.3 | 25±5.0 |
| Zn2+ | 0.15±0.02 | 160±20 | 1060±150 | 5.5±0.05a | |||
| 3 | Co2+ | 2.4±0.4 | 390±20 | 160±20 | 6.52±0.1 | 12±2.0 | 500±100 |
| Zn2+ | 0.87±0.1 | 950±120 | 1100±200 | 5.8±0.05a |
a Values taken from [31]