Squalene epoxidase
= Squalene epoxidase
<Squalene epoxidase> is a flavin-dependent <enzyme> that converts <squalene> to 2,3-epoxysqualene during sterol synthesis. The reaction introduces an oxygen-containing epoxide group before later cyclization steps construct the sterol ring system. In the human <enzyme>, <FAD> supports oxidation using molecular <oxygen> and reducing equivalents supplied through a reductase. <UniProtKB by the UniProt Consortium>[Human SQLE, Q14534: Function, Catalytic activity and Cofactor]{ref}
This step illustrates that biosynthetic pathways control both carbon skeletons and oxidation state. Adding a double-bond oxygen functionality and subsequently forming rings are different chemical operations performed by different <enzymes>. An assay of pathway output cannot locate an inhibition point without measurements of intermediates or a direct <enzyme> assay.