Photosynthetic oxidative phosphorylation

The importance of quinones with unsaturated side chains in respiratory, photosynthetic, blood-clotting, and oxidative phosphorylation processes has stimulated much research in synthetic methods. The important alkyl- or polyisoprenyltin reagents, eg, (71) or (72), illustrate significant conversions of 2,3-dimethoxy-5-methyl-l,4-ben2oquinone [605-94-7] (73) to 75% (74) [727-81-1] and 94% (75) [4370-61-0] (71—73). 

The thylakoid membrane is asymmetrically organized, or sided, like the mitochondrial membrane. It also shares the property of being a barrier to the passive diffusion of H ions. Photosynthetic electron transport thus establishes an electrochemical gradient, or proton-motive force, across the thylakoid membrane with the interior, or lumen, side accumulating H ions relative to the stroma of the chloroplast. Like oxidative phosphorylation, the mechanism of photophosphorylation is chemiosmotic. 

ATP is the primary high-energy phosphate compound produced by catabolism, in the processes of glycolysis, oxidative phosphorylation, and, in photosynthetic cells, photophosphorylation. Several enzymes then cany phosphoryl groups from ATP to the other nucleotides. Nucleoside diphosphate kinase, found in all cells, catalyzes the reaction... 

ADENOSINE DI-AND TRIPHOSPHATE. See Carbohydrates Phosphorylation (Oxidative) Phosphorylation (Photosynthetic). 

Formation of ATP by photosynthetic systems is often called photophosphorylation. Although photophosphorylation and oxidative phosphorylation are very similar, they do differ in a few details. The respiratory chain pumps protons... 

Substituted 2-aniIino-l,3,4-thiadiazoles uncouple oxidative phosphorylation in rat liver mitochondria and photosynthetic phosphorylation in spinach chloroplasts (75ZN(C)183). 

Bromoxynil (Hydroxybenzoni- trile) JjK. Photosynthetic electron transport inhibitor at the photosystem II receptor site, also uncouples oxidative phosphorylation... 

In Chapter 4 (Section 4.1D), we indicated that the radiation input of the sun to the earth s atmosphere averages 1366 W m-2 (the solar constant ). Some of the radiant energy is used to form ATP and NADPH in chloroplasts. In turn, these energy currencies lead to the reductive fixation of CO2 into a carbohydrate in photosynthesis (see Fig. 5-1). In the same photosynthetic cells, in other plant cells, and in animal cells, the carbohydrates formed during photosynthesis can serve as the energy source for mitochondrial respiration, which leads to the generation of ATP by oxidative phosphorylation. 

Photosynthetic Eiectron Transport Diverted Mitochondriai Eiectron Transport Oxidative Phosphorylation Photosynthetic Electron Transport (Hill Reaction) Carbon Metabolism -. n .n.ii... 

The photosystems have structural features in common that suggest a common evolutionary origin. Similarities in organization and molecular structure to those of oxidative phosphorylation suggest that the photosynthetic apparatus evolved from an early energy-transduction system. 

According to Simon (1953) five different mechanisms can be distinguished by which dinitrophenols affect the living cells. These include oxidative phosphorylation and photosynthetic phosphorylation which are considered as their main effects. Dinitrophenols in addition affect glycolytic phosphorylation, respiration and fermentation reaction. General other observed effects are protein denaturation and their inhibiting action on lipid synthesis, RNA and protein synthesis. 

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