10-Formyltetrahydrofolate
10-Formyltetrahydrofolate (10-CHO-THF) is a form of tetrahydrofolate that acts as a donor of formyl groups in anabolism. In these reactions 10-CHO-THF is used as a substrate in formyltransferase reactions.
Functions
Two equivalents of 10-CHO-THF are required in purine biosynthesis through the pentose phosphate pathway, where 10-CHO-THF is a substrate for phosphoribosylaminoimidazolecarboxamide formyltransferase.
10-CHO-THF is required for the formylation of methionyl-tRNA formyltransferase to give fMet-tRNA.[1]
Formation from methenyltetrahydrofolate
10-CHO-THF is produced from methylenetetrahydrofolate (CH2H4F) via a two step process. The first step generates 5,10-methenyltetrahydrofolate:[2]
- CH2H4F + NAD+ CH2H2F + NADH + H+
In the second step 5,10-methenyltetrahydrofolate undergoes hydrolysis:
- CH2H2F + H2O CHO-H4F +
The latter is equivalently written:
- 5,10-methenyltetrahydrofolate + H2O 10-formyltetrahydrofolate
10-CHO-THF is also produced by the reaction
- ATP + formate + tetrahydrofolate ADP + phosphate + 10-formyltetrahydrofolate
This reaction is catalyzed by formate-tetrahydrofolate ligase.
It can be converted back into tetrahydrofolate (THF) by formyltetrahydrofolate dehydrogenase or THF and formate by formyltetrahydrofolate deformylase.