Enzymic products of the 2,3-oxidosqualene analog having an ethyl residue at 10-position. First trapping of the trimethylcyclohexanone ring by lanosterol synthase

Incubation of squalene analog, (3RS)-(6E,10E,14E,18E)-10-ethyl-2,6,19,23-tetramethyl-2,3-epoxytetracosa-6,10,14,18,22-pentaene with 2,3-oxidosqualene-lanosterol cyclase from pig liver gave four products, consisting of two mono-, one tri- and one tetracyclic lanosterol homolog, suggesting that the steric bulk size at C-10 had greater influence on the polycyclization reaction, compared to that at C-15. The formation of the trimethylcyclohexanone ring by lanosterol synthases has never been reported before.