(a) Formaldehyde reacts non enzymatically with tetrahydrofolate to generate 5,10-methylenetetrahydrofolate. [14C] Formaldehyde can be used to prepare serine labeled in the β-carbon. What else would be needed?
(b) [14C] Serine, prepared as described above, is useful for many things, but you would probably not want to use it for studies on protein synthesis because it would label nucleic acids, carbohydrates, and lipids, as well as proteins. Indicate how each of these classes of compounds could become labeled by this precursor