1.17.8.1	physiological function	the reactions catalyzed by HpnC-HpnE constitute a three-step route for biosynthesis of squalene from farnesyl diphosphate. HpnD catalyzes formation of presqualene diphosphate from two molecules of farnesyl diphosphate, HpnC converts presqualene diphosphate to hydroxysqualene, and HpnE, a member of the amine oxidoreductase family, reduces hydroxysqualene to squalene	737313