Fig. 1: Hydrolysis reaction of N5,N10-methylenetetrahydrofolate as a source of formaldehyde.
From: An enzymatic activation of formaldehyde for nucleotide methylation
The cyclic form of CH2THF is activated by protonation leading to the iminium species (CH2THF+). This iminium is potentially in equilibrium with its carbinolamine counterpart (HOCH2THF). The carbinolamine intermediate can readily decompose into THF and formaldehyde (CH2O) in a reversible reaction28. CH2O can then serve as a direct source of methylene.
