The biosynthesis of beta-amyrin. Mechanism of squalene cyclization.
1. beta-Amyrin synthesized by pea seedlings in the presence of (3RS)-[2-(14)C,(4R)-4-(3)H(1)]mevalonic acid (for nomenclature see Cahn, Ingold & Prelog, 1956) was subjected to a series of degradations to locate the positions within the molecule of the incorporated tritium. 2. The location of five of the six labelled hydrogen atoms at C-3, C-9, C-18 and C-19 (two) confirms that the mechanism of cyclization of squalene expected from the biogenetic isoprene rule is functioning in vivo.
D002247:Carbon Isotopes; D002855:Chromatography, Thin Layer; D008798:Mevalonic Acid / Q000378:metabolism*; D010616:Phenanthrenes / Q000096:biosynthesis*; D010944:Plants / Q000378:metabolism*; D013185:Squalene / Q000096:biosynthesis*; D014316:Tritium
D002247:Carbon Isotopes; D010616:Phenanthrenes; D014316:Tritium; D013185:Squalene; D008798:Mevalonic Acid