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Absolute Configuration of Hydroxysqualene. An Intermediate in Bacterial Hopanoid Biosynthesis
- Pan, Jian-Jung, Ramamoorthy, Gurusankar, Poulter, C. Dale
- Organic letters 2016 v.18 no.3 pp. 512-515
- bacteria, biosynthesis, chemical structure, hopanoids, solvolysis, spectroscopy, squalene
- Squalene (SQ) is a key intermediate in hopanoid biosynthesis. Many bacteria synthesize SQ from farnesyl diphosphate (FPP) in three steps: FPP to (1R,2R,3R)-presqualene diphosphate (PSPP), (1R,2R,3R)-PSPP to hydroxysqualene (HSQ), and HSQ to SQ. Chemical, biochemical, and spectroscopic methods were used to establish that HSQ synthase synthesizes (S)-HSQ. In contrast, eukaryotic squalene synthase catalyzes solvolysis of (1R,2R,3R)-PSPP to give (R)-HSQ. The bacterial enzyme that reduces HSQ to SQ does not accept (R)-HSQ as a substrate.