title: Stereochemistry of phytoene biosynthesis by isolated chloroplasts.
abstract: The incorporation of [2-(14)C,(5R)-5-(3)H(1)]MVA* and [2-(14)C,5-(3)H(2)]MVA into geranylgeraniol and phytoene by a preparation of ;non-aqueous' bean leaf chloroplasts has been studied. In the formation of phytoene from two molecules of geranylgeranyl pyrophosphate, the loss of hydrogen is stereospecific, the hydrogen atom lost from C-1 of each molecule of geranylgeranyl pyrophosphate being that which was originally the pro-S hydrogen atom from C-5 of mevalonate. All the pro-R hydrogen atoms from C-5 of mevalonate are retained. These results with a cell-free system confirm and extend the observations made in previous work with tomato slices.
mesh_terms: D000438:Alcohols / Q000096:biosynthesis; D000470:Alkaloids / Q000096:biosynthesis*; D002247:Carbon Isotopes; D002474:Cell-Free System; D002736:Chloroplasts / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D008798:Mevalonic Acid / Q000378:metabolism; D013237:Stereoisomerism; D013729:Terpenes / Q000096:biosynthesis*; D014316:Tritium
chemical_list: D000438:Alcohols; D000470:Alkaloids; D002247:Carbon Isotopes; D011756:Diphosphates; D013729:Terpenes; D014316:Tritium; D006859:Hydrogen; D008798:Mevalonic Acid