Journal of Lipid Research, Vol 27, 1-10, Copyright © 1986 by Lipid Research, Inc.
Oxidative demethylation of lanosterol in cholesterol biosynthesis: accumulation of sterol intermediates
A Shafiee, JM Trzaskos, YK Paik and JL Gaylor
With [3H-24,25]-dihydrolanosterol as substrate, large-scale metabolic
formation of intermediates of lanosterol demethylation was carried out to
identify all compounds in the metabolic process. Utilizing knowledge of
electron transport of lanosterol demethylation, we interrupted the
demethylation reaction allowing accumulation and confirmation of the
structure of the oxygenated intermediates lanost-8-en-3 beta,32-diol and 3
beta-hydroxylanost-8-en-32-al, as well as the demethylation product
4,4-dimethyl-cholesta-8,14-dien-3 beta-ol. Further metabolism of the delta
8.14-diene intermediate to a single product 4,4-dimethyl- cholest-8-en-3
beta-ol occurs under interruption conditions in the presence of 0.5 mM
CN-1. With authentic compounds, each intermediate has been rigorously
characterized by high performance liquid chromatography and gas-liquid
chromatography plus mass spectral analysis of isolated and derivatized
sterols. Intermediates that accumulated in greater abundance were further
characterized by ultraviolet, 1H-NMR, and infrared spectroscopy of the
isolated sterols.