Question

S-Adenosylmethionine A. contains a charged sulfur that carries the methyl group to be transferred. B. yields \(\alpha\) -ketobutyrate in the reaction in which the methyl is transferred. C. donates a methyl group in a freely reversible reaction. D. generates \(\mathrm{H}_{2} \mathrm{S}\) by transsulfuration. E. provides the carbons for the formation of cysteine.

Short answer

Answer: S-Adenosylmethionine contains a charged sulfur that carries the methyl group to be transferred.

Step-by-step solution

S-Adenosylmethionine (SAM) is a molecule that plays a crucial role in methylation reactions in biological systems. By analyzing the given information, we can conclude that: - A. contains a charged sulfur that carries the methyl group to be transferred: This statement is true. SAM contains a positively charged sulfur atom, which carries the methyl group that will be transferred to other molecules in the methylation reaction. #Step 2: Explanation of other statements#

Now that we have identified the true statement regarding S-Adenosylmethionine, let's analyze the remaining statements: - B. yields α-ketobutyrate in the reaction in which the methyl is transferred: This statement is false. In the reaction where SAM donates a methyl group, it is converted to S-adenosylhomocysteine, not α-ketobutyrate. - C. donates a methyl group in a freely reversible reaction: This statement is false. Although SAM can donate a methyl group, the reaction is not freely reversible in most cases, as the forward reaction is usually favored. - D. generates \(\mathrm{H}_{2} \mathrm{S}\) by transsulfuration: This statement is false. Transsulfuration is a process that involves the transfer of a sulfur atom from one molecule to another, generating hydrogen sulfide (H2S) as a byproduct. However, this process does not involve SAM. - E. provides the carbons for the formation of cysteine: This statement is false. Although SAM is involved in the synthesis of cysteine, it does not provide the carbons directly. Instead, it plays a role in the conversion of homocysteine to cysteine. In conclusion, the correct answer is A - S-Adenosylmethionine contains a charged sulfur that carries the methyl group to be transferred.