Table I.
Kinetic constants of wild-type SHT, THT, and chimeric proteins with tyramine and serotonin as amine substrates
Feruloyl-CoA (250 μm) was used as the acyl donor. ND, Not detected.
| Enzyme
|
Tyramine
|
Serotonin
|
||||
|---|---|---|---|---|---|---|
| Km | Vmax | Vmax/Km | Km | Vmax | Vmax/Km | |
| μm | nkat mg−1 | μm | nkat mg−1 | |||
| SHT | 1,165 | 17.0 | 0.0146 | 73 | 6.5 | 0.0890 |
| THT | 40 | 66.8 | 1.6750 | ND | ND | ND |
| CH1 | 720 | 59.1 | 0.0820 | ND | ND | ND |
| CH2 | 7,400 | 11.2 | 0.0015 | 250 | 6.6 | 0.0264 |
| CH3 | 16,658 | 9.4 | 0.0005 | 2,360 | 27.0 | 0.0114 |
| CH4 | 10,650 | 10.1 | 0.0009 | ND | ND | ND |
| CH5 | 11,486 | 13.0 | 0.0011 | 942 | 10.8 | 0.0115 |