Reaction mechanism of flavin-dependent hydroxylation. Evolution of a non-imitable enzyme

Analysis of the partially refined X-ray crystallographic structure of the active site of p-hydroxybenzoate hydroxylase shows clearly that the enzyme is complementary to a flavin C4,C4a-dioxetane derivative. A mechanism is proposed based on such an intermediate as the oxenoid transferring agent. A non-enzymatic analogue of this reaction is not known in organic chemistry. A possible evolutionary pathway for such a non-imitable enzyme is discussed.