Cells That Secrete Epinephrine Must Contain Which Enzymes

Question

Cells that secrete epinephrine must contain which enzymes?
A) dopamine fi -hydroxylase, tyrosine fi -hydroxylase, and dopa decarboxylase only
B) phenylethanolamine N -methyl transferase and dopa decarboxylase only
C) tyrosine fi -hydroxylase and phenylethanolamine N -methyl transferase only
D) dopamine fi -hydroxylase, tyrosine fi -hydroxylase, phenylethanolamine N -methyl transferase, and dopa decarboxylase
E) dopamine fi -hydroxylase and dopa decarboxylase only

Accepted Answer

The synthesis of epinephrine involves several steps, starting with the amino acid tyrosine. Tyrosine is first hydroxylated by tyrosine hydroxylase to form DOPA, which is then decarboxylated by dopa decarboxylase to form dopamine. Dopamine is then hydroxylated by dopamine β-hydroxylase to form norepinephrine. Finally, norepinephrine is methylated by phenylethanolamine N-methyltransferase (PNMT) to form epinephrine. Therefore, all four enzymes are necessary for the synthesis of epinephrine.