Kinetic and pH studies on human phenylethanolamine N-methyltransferase

- hPNMT operates by an ordered mechanism with AdoMet binding before norepinephrine.
- Epinephrine and AdoHcy both showed evidence of product inhibition.
- THIQ inhibitors compete with phenylethanolamine but are uncompetitive with AdoMet.
- Binding of AdoMet increased the binding affinity of the second substrate/inhibitor.
- log V/K pH profiles are all bell shaped with slopes of unity on each side.