TABLE 5.
Kinetic parameters of halomethane:bisulfide/halide ion methyltransferase
| Methyl donor | Kinetic parametera
|
Acceptor anion | Kinetic parametera
|
||||
|---|---|---|---|---|---|---|---|
| App. Km (μM) | App. Vmax (U/mg) | Vmax/Km (U/mg/μM) | App. Km (mM) | App. Vmax (U/mg) | Vmax/Km (U/mg/μM) | ||
| CH3Clb | 7 | 42.6 | 6.1 | Cl−c | 11.6 | 105 | 9.1 |
| CH3Brb | 30 | 49.4 | 1.7 | Br−c | 5.1 | 45.9 | 9.0 |
| CH3Id | 36 | 87.0 | 2.4 | I−e | 0.37 | 80.1 | 216 |
| CH3SH | —f | —f | HS−c | 1.7 | 241 | 142 | |
a
The apparent (App.) Km and Vmax values are the means of duplicate experiments. The relative standard deviations for Km and Vmax were 6.3 and 4.7%, respectively.
b
Acceptor anion, 3 mM I−.
c
Methyl donor, 0.4 mM CH3I.
d
Acceptor anion, 120 mM Cl−.
e
Methyl donor, 0.5 mM CH3Br.
f
—, CH3SH does not act as a methyl donor with any acceptor ion.