TABLE 4.
Substrate anion range of methyltransferase
| Substrate anion | Ratea |
|---|---|
| I− | 100 |
| F− | <0.1 |
| Cl− | 28 ± 0.6b |
| Br− | 17 ± 0.8 |
| HS− | 22 ± 5.3 |
| NO2− | 4.1 ± 0.3 |
| CN− | 3.6 ± 0.8 |
| SCN− | <0.4 (3.6 ± 0.3)c |
a
Rate of methylation by the activated enzyme on a molar basis relative to that with I− as the substrate anion in 50 mM phosphate buffer (pH 7.0) with 0.5 mM CH3Cl as the methyl donor and 10 mM substrate anion as the sodium salt at 25°C. With each anion the rate is corrected for any chemical conversion observed. Values are means of three replicates ± standard deviations.
b
Determined by using 10 mM 37Cl− as the anion as described in Materials and Methods.
c
Rate of methylation with 50 mM SCN−.