This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Norepinephrine to epinephrine conversion requires which enzyme: 
Select and explain. 
A. Phenylethanolamine-N-methyltransferase, B. Transaldolase, C. Tyrosine hydroxylase, D. Alpha ketoglutarate
A: Phenylethanolamine-N-methyltransferase
Answer: A: Phenylethanolamine-N-methyltransferase 
Explanation: Ans:A.)Phenylethanolamine-N-methyltransferaseMethylation of norepinephrine by S-adenosyl-methionine gives epinephrine, reaction being catalysed by phenylethanolamine N-methyltransferase Phenylethanolamine N-methyltransferase (PNMT)It is an enzyme found in the adrenal medulla that conves Norepinephrine (Noradrenaline) to Epinephrine (Adrenaline).PNMT is positively influenced by coisol, which is produced in the adrenal coex.S-adenosyl-L-methionine ('SAM') is a required cofactor.