Retention of the label during the conversion of [3-3H] squalene into (3S)-2,3-oxidosqualene catalyzed by mammalian squalene oxidase.

Squalene epoxidase is the only known flavoprotein that catalyzes the epoxidation of an olefin. In order to test the possibility of a catalytic non-heme metal-based mechanism, the conversion of chemically synthesized [3-3H]squalene into [3H]2,3-oxidosqualene, by partially purified pig liver squalene epoxidase, was studied. No exchange of the labeled hydrogen could be observed, ruling out a mechanism involving, e.g., an iron carbene type species at C-3.