Synthesis of dehydrosqualene in microsomal fraction of Saccharomyces cerevisiae.

When the microsomal fraction of Saccharomyces cerevisiae was incubated with farnesyl pyrophosphate or presqualene pyrophosphate in the presence of Mn²⁺, dehydrosqualene was formed. Incubation of the reaction mixture in the presence of NADPH gave squalene, not dehydrosqualene, as the product. Little dehydrosqualene was formed when Mn²⁺ was replaced with Mg²⁺. These observations suggest that dehydrosqualene formation is closely associated with squalene synthesis in yeast, which synthesizes neither carotenes nor related pigments.