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.

EnzymeTyramineSerotonin
KmVmaxVmax/KmKmVmaxVmax/Km
μmnkat mg−1μmnkat mg−1
SHT1,16517.00.0146736.50.0890
THT4066.81.6750NDNDND
CH172059.10.0820NDNDND
CH27,40011.20.00152506.60.0264
CH316,6589.40.00052,36027.00.0114
CH410,65010.10.0009NDNDND
CH511,48613.00.001194210.80.0115