Characterization of a photosynthesizing reconstituted spinach chloroplast preparation: regulation by primer, adenylates, ferredoxin, and pyridine nucleotides
A particulate preparation (MgP) capable of photosynthetic CO/sub 2/ assimilation without the addition of stromal protein was obtained by rupturing whole spinach (Spinacia oleracea var. America) chloroplasts in 15 millimolar MgCl/sub 2/ buffered with Tricine at pH 8.5. This CO/sub 2/ assimilation was dependent upon light, inorganic phosphate, ferredoxin, ADP, NAD or NADP, and primer. Excepting glycolate, the products of CO/sub 2/ fixation by MgP were similar to those found with whole chloroplasts. Glycerate-3-phosphate (PGA), fructose-1,6-bisphosphate (FBP), and ribose-5-phosphate (R5P) but not fructose-6-P (F6P) functioned as primers. Concentrations of PGA and FBP but not of R5P higher than 2 millimolar where inhibitory to CO/sub 2/ fixation. A lag of CO/sub 2/ fixation was observed with PGA and FBP but not with R5P. This lag as well as inhibition by NADP, ADP, and ATP in the FBP-primed preparation was eliminated by an equimolar mixture of FBP plus F6P indicating FBPase as the sensitive site. NADP, ADP, and ATP also blocked CO/sub 2/ fixation by the PGA-fortified preparation but inhibition was even more sensitive than that observed when FBP was added. Inhibition by AMP in the PGA and FBP-primed preparations was not affected by the addition of F6P. When R5P was the starting primer, inhibition of CO/sub 2/ fixation was relatively insensitive to the adenylates and NADP. In contrast to the parent whole chloroplast, CO/sub 2/ fixation by MgP was insensitive to high (5 millimolar) inorganic phosphate. Depending upon the ferredoxin concentration, NAD was as effective as NADP in supporting CO/sub 2/ fixation.
- Research Organization:
- Brandeis Univ., Waltham, MA
- OSTI ID:
- 5799740
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 69:1; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLOROPLASTS
ELECTROMAGNETIC RADIATION
MAGNESIUM COMPOUNDS
MAGNESIUM PHOSPHATES
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANTS
RADIATIONS
RESPONSE MODIFYING FACTORS
STIMULATION
SYNTHESIS
VISIBLE RADIATION