Protostadienol synthase

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Protostadienol synthase (EC 5.4.99.32), also called PdsA, is an enzyme that helps build helvolic acid, a steroidal antibiotic. It acts as a mutase, cyclizing and rearranging (3S)-2,3-epoxy-2,3-dihydrosqualene to form (17Z)-protosta-17(20),24-dien-3beta-ol (protostadienol). This product is a key precursor in helvolic acid biosynthesis. Systematic name: (3S)-2,3-epoxy-2,3-dihydrosqualene mutase (cyclizing, (17Z)-protosta-17(20),24-dien-3beta-ol-forming).