Photophosphorylation, Uncoupling, Amines, Proton Motive Force, Chloroplasts, Chemiosmotic Theory Intact chloroplasts exposed to hypotonic assay conditions are capable o f photophosphorylating exogenous ADP. The rate of phosphorylation by these unbroken plastids is increased by 10—50% upon the addition of low concentrations (< mM) of NH 3 or CH3N H 2. Stimulation o f phosphory­ lation is abolish...

In NADP-malic enzyme-type C(4) plants such as maize (Zea mays L.), efficient transport of oxaloacetate and malate across the inner envelope membranes of chloroplasts is indispensable. We isolated four maize cDNAs, ZmpOMT1 and ZmpDCT1 to 3, encoding orthologs of plastidic 2-oxoglutarate/malate and general dicarboxylate transporters, respectively. Their transcript levels were upregulated by light...

Chloroplasts originate through the endosymbiotic integration of a host and a photosynthetic symbiont, with processes established within the host for the biogenesis and maintenance of the nascent chloroplast. It is thought that several photosynthetic eukaryotes have replaced their original chloroplasts with others derived from different source organisms in a process termed "serial endosymbiosis ...

1. Ammonium chloride is a poor uncoupler of photophosphorylation in subchloroplast particles. In the presence of valinomycin the inhibition of photophosphorylation by NH&l is greatly enhanced. 2. The enhancement of the ammonium chloride uncoupling of phosphorylation by valinomycin was less pronounced in chloroplasts than in subchloroplast particles. 3. The light-dependent uptake of ammonium ion...

As the global energy demand continues to increase, interest in photosynthetic conversion is growing accordingly. Chloroplasts, organelles present plants and algae, are attractive candidates for construction of bio solar cells; however, they have been less studied because their complex membrane system, which restricts electrochemical communication with an electrode surface. Nevertheless, this wo...

Using fluorescence spectroscopy, we have demonstrated that isolated envelope membranes from mature spinach chloroplasts catalyze the phototransformation of endogenous protochlorophyllide into chlorophyllide in presence of NADPH, but not in presence of NADH. Protochlorophyllide reductase was characterized further using monospecific antibodies (anti-protochlorophyllide reductase) raised against t...

In intact (type A) chloroplasts isolated from mesophyll protoplasts of maize (Zea mays L. convar. KSC 360) the flash-induced 515 nanometer absorbance change was much higher than in conventionally prepared (types B and C) chloroplasts. The 515 nanometer signal of type A chloroplasts exhibited a biphasic rise: the initial very fast rise (rise time <<1 millisecond) was followed by a slow increase ...

Concentrations of total CoAs in chloroplasts freshly isolated from spinach and peas were 10-20 microM, assuming a stromal volume of 66 microl per mg of chlorophyll. Acetyl-CoA and CoASH constituted at least 90% of the total CoA in freshly isolated chloroplasts. For a given chloroplast preparation, the concentration of endogenous acetyl-CoA was the same when extractions were performed using HClO...

We asked how chloroplasts in a unicellular marine alga are replicated and partitioned at cell division so that each daughter cell will receive the appropriate number of copies. The data were obtained simply by counting chloroplasts in pairs of daughter cells immediately after cell division. The results show that chloroplast partitioning is not always equal; however, it is equal much more often ...

Within the chloroplasts reactive oxygen species (ROS) are generated during photosynthesis and stressful conditions. Excessive ROS damages chloroplasts and reduces photosynthesis if not properly detoxified. In this current study, we document that chloroplasts produce melatonin, a recently-discovered plant antioxidant molecule. When N-acetylserotonin, a substrate for melatonin synthesis, was fed ...