A 26-year-old chef with schizophrenia has been admitted to the inpatient psychiatry service after her second florid episode in a year. Her physician prescribes chlorpromazine and alprazolam to be...

A 26-year-old chef with schizophrenia has been admitted to the inpatient psychiatry service after her second florid episode in a year. Her physician prescribes chlorpromazine and alprazolam to be taken immediately.At the urging of her family, the patient also resumes taking the haloperidol she was prescribed by another doctor after her earlier episodes. After a week in the hospital, her nurses notice a resting “head-nod” tremor, as well as slowness in movements. Her facial expression is also markedly diminished. A review of medication reveals she is taking high doses of two antipsychotics, which are considered the cause of her parkinsonism.The haloperidol is discontinued and L-dopa begun to alleviate symptoms. Which of the following enzymes catalyzes the rate-limiting step required for Ldopa to be converted to dopamine in the brain?

A. Phenylalanine hydroxylase

B. Tyrosine hydroxylase

C. Dopa decarboxylase

D. Monoamine oxidase A

E. Monoamine oxidase B