Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea

Kucha is a rare variety of tea tree that produces the non-stimulatory theacrine instead of caffeine. Here the authors show that theacrine synthase from Kucha has N9-methyltransferase activity resulting from amino acid substitutions that explain substrate specificity and could potentially guide production of caffeine-free tea.