Assay of the possible organization of particle-bound enzymes with squalene synthetase and squalene oxidocyclase systems

Lanosterol was biosynthesized in pig liver homogenate from [4,8,12-(14)C(3)]farnesyl pyrophosphate and [4S-4-(3)H]NADPH through the intermediary formation of squalene labelled asymmetrically with (3)H. The biosynthetic lanosterol, freed from labelled 24,25-dihydrolanosterol, which was also synthesized, was converted into 24,25-dihydrolanosteryl acetate and subjected to chemical degradations to locate the position(s) of the (3)H label in the molecule. The ratio of (3)H at C-11 to that at C-12 was found to be 1.28. Although a certain inequality of labelling was thus indicated, experimental uncertainties did not permit the conclusion that the asymmetrically labelled squalene might have been cyclized preferentially from one end.