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In enzymology, a chloroplast protein-transporting ATPase (EC 3.6.3.52) is an enzyme that catalyzes the chemical reaction ATP + H 2 O ⇌ {\displaystyle \rightleftharpoons } ADP + phosphate Thus, the two substrates of this enzyme are ATP and H 2 O , whereas its two products are ADP and phosphate .
ADP and Pi (inorganic phosphate) bind spontaneously to the three β subunits of the F 1 domain, so that every time it goes through a 120° rotation ATP is released (rotational catalysis). The F o domains sits within the membrane, spanning the phospholipid bilayer, while the F 1 domain extends into the cytosol of the cell to facilitate the use ...
In plants, ATP synthase is also present in chloroplasts (CF 1 F O-ATP synthase). The enzyme is integrated into thylakoid membrane; the CF 1-part sticks into stroma, where dark reactions of photosynthesis (also called the light-independent reactions or the Calvin cycle) and ATP synthesis take place. The overall structure and the catalytic ...
F-ATP synthases are identical in appearance and function except for the mitochondrial F 0 F 1-ATP synthase, which contains 7-9 additional subunits. [12] The electrochemical potential is what causes the c-ring to rotate in a clockwise direction for ATP synthesis. This causes the central stalk and the catalytic domain to change shape.
H + ions from the lumen of the thylakoid into the cytosol of a cyanobacterium or the stroma of a chloroplast. A steep H + gradient is formed, which allows chemiosmosis to occur, where the thylakoid, transmembrane ATP-synthase serves a dual function as a "gate" or channel for H + ions and a catalytic site for the formation of ATP from ADP + a PO ...
An uncoupler or uncoupling agent is a molecule that disrupts oxidative phosphorylation in prokaryotes and mitochondria or photophosphorylation in chloroplasts and cyanobacteria by dissociating the reactions of ATP synthesis from the electron transport chain.
ATPases (or ATP synthases) are membrane-bound enzyme complexes/ion transporters that combine ATP synthesis and/or hydrolysis with the transport of protons across a membrane. ATPases can harness the energy from a proton gradient, using the flux of ions across the membrane via the ATPase proton channel to drive the synthesis of ATP. Some ATPases ...
The thylakoid ATP synthase is a CF1FO-ATP synthase similar to the mitochondrial ATPase. It is integrated into the thylakoid membrane with the CF1-part sticking into the stroma. Thus, ATP synthesis occurs on the stromal side of the thylakoids where the ATP is needed for the light-independent reactions of photosynthesis.