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How is squalene converted into lanosterol during cholesterol synthesis?
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Steroid
Many important physiological functions of vertebrates are controlled by steroid hormones.
The conversion of squalene into lanosterol is a critical step in the biosynthesis of cholesterol.
The process occurs through the following sequence:
- Oxidation: One end of the linear squalene molecule is oxidized to form squalene 2,3-oxide.1
- Cyclization and Rearrangement: This oxide intermediate undergoes an enzyme-controlled intramolecular reaction (cyclization) followed by a structural rearrangement to yield lanosterol.1
This reaction is believed to be initiated by the introduction of a positive charge into the oxide ring, a process that mirrors nonenzymic, acid-catalyzed cyclizations of unsaturated hydrocarbons with structures similar to squalene. Once lanosterol is formed, it undergoes further structural modifications to become cholesterol.1