NANP Board Practice Exam

What can Methionine be converted to and used as in many biochemical pathways?

1. Cysteine

2. Glutamine

3. S-adenosylmethionine (SAM)

4. Taurine

The correct answer is: Cysteine

Methionine can indeed be converted to S-adenosylmethionine (SAM), which plays a crucial role in many biochemical processes. SAM is considered a universal methyl donor involved in methylation reactions that modify DNA, RNA, proteins, and lipids. This conversion is significant because SAM not only participates in critical biological pathways but also serves as a precursor for the synthesis of other molecules, including cysteine through the transsulfuration pathway. While cysteine itself is derived from methionine, it is important to recognize that SAM serves as an intermediary that highlights the broader metabolic role of methionine. Devoting attention to the role of SAM underlines its significance in methylation and the synthesis of various compounds essential for cellular functions. Therefore, the conversion of methionine to S-adenosylmethionine aligns with a fundamental biochemical pathway that demonstrates methionine's versatility and importance in metabolic processes.