The rate limiting step for norepinephrine synthesis is:
Ans. (B) Conversion of tyrosine to DOPA(Ref: Katzung 10/e p78; KDT 8th/e p136)Rate limiting enzyme in norepinephrine synthesis is tyrosine hydroxylase that catalyses the conversion of tyrosine to dopa. In ACh synthesis, rate limiting step is uptake of choline by the neurons.
Conversion of phenylalanine to tyrosine
Conversion of tyrosine to DOPA
Conversion of DOPA to dopamine
Conversion of dopamine to norepinephrine
Adrenergic System