Which vitamin functions as a cofactor for the conversion of dopamine to norepinephrine?

The vitamin that acts as a cofactor for the conversion of dopamine to norepinephrine is Vitamin C. This conversion process is facilitated by the enzyme dopamine β-hydroxylase, which requires Vitamin C as a cofactor to carry out the hydroxylation of dopamine, leading to the production of norepinephrine.

Vitamin C, also known as ascorbic acid, plays a crucial role in various biochemical reactions within the body, including its involvement in the synthesis of neurotransmitters. By participating in the hydroxylation reaction, Vitamin C helps in ensuring an adequate supply of norepinephrine, a critical neurotransmitter involved in the body's fight or flight response, among other functions.

In contrast, Vitamin B6 is primarily involved in the synthesis of neurotransmitters such as serotonin and GABA but is not directly required for the conversion of dopamine to norepinephrine. Biotin is a cofactor for carboxylation reactions, and folate is essential for nucleotide synthesis and also plays a role in amino acid metabolism, but neither is involved in this specific conversion pathway. Therefore, Vitamin C is the correct answer for this question.