Human L-3,4-dihydroxyphenylalanine (l-DOPA) decarboxylase is the enzyme responsible for the synthesis of the essential neurotransmitters dopamine and serotonin derived by decarboxylation from the corresponding amino acids l-DOPA and L-5-hydroxytryptophan. The therapy for Parkinson’s disease is a combination of l-DOPA, that can cross the blood-brain barrier and reach neuronal DDC to increase dopamine content, with a peripheral inhibitor in order to modulate activity of peripheral decarboxylase (DDC) and allow a greater l-DOPA content to reach the brain. DDC belongs to the pyridoxal 5’-phosphate a-decarboxylases group together with other enzymes, such as histidine decarboxylase, glutamate decarboxylase and cysteine sulfininc acid decarboxylase, acting on amino acids and catalyzing the synthesis of important amines. The eventual work should be devoted to find a more promising and personalized therapeutic approach starting from a design of molecules that specifically are able to bind to DDC in order to modulate its activity.