Which of the following conversion is irreversible: (A) Formyl THFA to Methenyl-THFA, (B) Methenyl THFA to Methylene-THFA, (C) Methylene THFA to Methyl-THFA, (D) All of the above
Answer is C. One carbon groups are formed from various sources. Except the formation of methyl-THFA The other one-carbons are interconveible The only way of regeneration of active THFA from methyl-THFA is the methionine synthase reaction.