beta. -carotene synthesis in spinach chloroplasts is tightly linked to photosynthetic carbon metabolism
When purified, highly intact spinach chloroplasts were illuminated in the presence of NaH/sup 14/CO/sub 3/, the largest portion of acetate derived compounds formed was ..beta..-carotene and not fatty acids (20 and 2.5 natoms C incorporated/mg chlorophyll x h when 5 mM NaH /sup 14/CO/sub 3/ was used). From isotopic dilution experiments applying glyceraldehyde 3-P, dihydroxyacetone-P, 3-phosphoglycerate (3-PGA), 2-PGA, phosphoenolpyruvate (PEP) and pyruvate, respectively, evidence was obtained that acetyl-CoA to form isopentenyl-PP (IPP) originates from a low capacity but highly effective flow from photosynthetic CO/sub 2/-fixation via 3-PGA - 2-PGA - PEP - pyruvate. Phosphoglycerate mutase in chloroplasts, of which the presence hitherto was not unequivocally proven, was detected by (i) latency technique and (ii) feeding/1-/sup 14/C/glycerate and following 3-PGA, 2-PGA, PEP and pyruvate level in chloroplasts and suspension medium. From highly effective synthesis of ..beta..-carotene from CO/sub 2/ conclusion may be drawn that pathways for both, acetyl compounds and IPP, to form isoprenoids must exist in chloroplasts.
- Research Organization:
- Botanisches Institute, Hannover, West Germany
- OSTI ID:
- 5872047
- Report Number(s):
- CONF-8707108-; TRN: 87-039635
- Journal Information:
- Plant Physiol., Suppl.; (United States), Vol. 83:4; Conference: Annual meeting of the American Society of Plant Physiologists, St. Louis, MO, USA, 19 Jul 1987
- Country of Publication:
- United States
- Language:
- English
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CAROTENOIDS
BIOSYNTHESIS
CHLOROPLASTS
ENZYME ACTIVITY
ANABOLISM
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CARBON DIOXIDE FIXATION
ISOTOPE DILUTION
PHOTOSYNTHESIS
SPINACH
CELL CONSTITUENTS
CHEMICAL REACTIONS
FOOD
HYDROCARBONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METABOLISM
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PIGMENTS
PLANTS
SYNTHESIS
TERPENES
TRACER TECHNIQUES
VEGETABLES
551001* - Physiological Systems- Tracer Techniques