Chapter 18, Problem 21P

Interpretation Introduction

(a) Interpretation:

Formaldehyde reacts non-enzymatically with tetrahydrofolate to generate $5,10$ - methylenetetrahydrofolate. [14C] Formaldehyde can be used to prepare serine labeled in the $\beta$ -carbon. The other things that would be needed are to be mentioned.

Concept introduction:

Tetrahydrofolate is a coenzyme derived from folic acid and participates in the variation of the Schiff's base mechanism pattern. Serine hydroxymethyltransferase acts as a catalyst for the reversible conversion of serine and glycine amino acids.

Interpretation Introduction

(b) Interpretation:

$\left[14\text{C}\right]$ 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.

Concept introduction:

Methylene-tetrahydrofolate is formed from the $\beta$ -carbon of serine and can be further oxidized to form carbon-dioxide. This can be predicted as a result of the sequential reactions of methylene-THF dehydrogenase, cyclohydrolase and $10$ -formyl THF.