DDC enzyme activity
In the periphery: metabolizes L-dopa into peripheral dopamine4,5
COMT enzyme activity
In the periphery: metabolizes L-dopa into 3-O-methyldopa (3-OMD)4,6 The metabolic activity of the COMT enzyme may increase when peripheral L-dopa inactivation is shifted from DDC to COMT1,7-9
Artistic depiction of L-dopa is provided for illustration purposes only.references+
EDS=excessive daytime sleepiness; MCI=mild cognitive impairment; RBD=rapid eye movement sleep behavior disorder.
Reprinted from The Lancet, Vol. 386, Kalia LV, Lang AE, Parkinson’s disease, Pages 896-912, Copyright (2015), with permission from Elsevier.