Table 1. In Vitro Reaction Kinetics for a-Factor Peptides Methylated by His-Ste14p.
compound | Vmax (pmol min–1 mg–1)a | Km(app) (μM)b | Vmax/Km (pmol min–1 mg–1 μM–1)a,b |
---|---|---|---|
AFC(22) | 870 ± 15 | 15.9 ± 0.9 | 54 |
16 | 947 ± 4 | 6.6 ± 0.2 | 143 |
17 | 1919 ± 30 | 12.2 ± 0.1 | 157 |
18(22) | 762 ± 28 | 14.6 ± 0.3 | 52 |
19 | 217 ± 3 | 27.8 ± 1 | 7.0 |
Reported as pmol of methyl groups transferred to substrate.
Because these experiments were performed at a single concentration of SAM and the biphasic nature of the membrane suspension makes the concentration of the peptide substrate unknown (because of partitioning into the lipid membranes), these experiments provide only apparent values for Km.