Catecholamines (i.e., dopamine, norepinephrine, and epinephrine) are important adrenal medullary hormones which play a role in the response for emergency situations. The following statements are made with reference to this:

A. Catecholamines can easily cross the blood-brain barrier.
B. Dopa decarboxylase (DD) is a soluble enzyme that converts L-dopa to dopamine.
C. Dopamine β-hydroxylase (DBH) is a particulate enzyme carrying copper in its active site and it converts dopamine to epinephrine.
D. Phenylethanolamine-N-methyltransferase (PNMT) is a soluble enzyme that is induced by glucocorticoids.

Which one of the following has the correct combination of statements?

Correct option is B

Explanation-

Statement A - Catecholamines can easily cross the blood-brain barrier - INCORRECT
Catecholamines (dopamine, norepinephrine, epinephrine) are polar molecules and cannot easily cross the blood-brain barrier. That’s why L-DOPA (a precursor) is used in treatment (e.g., for Parkinson’s), because L-DOPA can cross the barrier.
Statement B -  Dopa decarboxylase (DD) is a soluble enzyme that converts L-DOPA to dopamine  - CORRECT
This enzyme, also known as aromatic L-amino acid decarboxylase, converts L-DOPA → dopamine. It is a soluble cytosolic enzyme.
Statement C -  Dopamine β-hydroxylase (DBH) is a particulate enzyme carrying copper in its active site and it converts dopamine to epinephrine - INCORRECT
DBH does carry copper and is a particulate enzyme, but it converts dopamine to norepinephrine, not epinephrine. Epinephrine is made from norepinephrine by PNMT.
Statement D -  Phenylethanolamine-N-methyltransferase (PNMT) is a soluble enzyme that is induced by glucocorticoids - CORRECT
PNMT converts norepinephrine → epinephrine. It is a soluble cytosolic enzyme and is induced by glucocorticoids (especially cortisol in the adrenal medulla).

Final Answer:
Correct statements: B and D (Option b)