, hydrolysis or synthesis of ATP.

8 ATP, ADP, and Pi transport.
The mechanism of ATP synthesis (catalyzing conversion of ADP + Pi to ATP must be coordinated for production of ATP as needed.

What is the purpose of protons?
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We will attempt to explain below the mechanism of γ-subunit rotation taking into account the peculiarities of twisted carbon nanotube nanomotor rotation, stabilization–destabilization of protein molecules by polyvalent anions–cations, principles of ion channel functioning, complex structure of ATP synthase, including the γ-subunit, and a complex interdependence of processes coupled in ATP synthesis with swelling–shrinkage, as suggested earlier (Kasumov et al. , , , , , ). In our opinion, such a mechanism of ATP synthesis occurs in vivo and may not be compatible with some of the data obtained in vitro, where the rate of ATP synthesis is relatively very low.


10 DNA, RNA, and Protein Synthesis - 28 cards

What is the major force that drives ATP synthesis in the ATP synthase functioning?
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Later, this chemiosmotic hypothesis was refined in terms of proton transfer (Mitchell ), and the idea was proposed that the hydrophobic component of ATPase-F0 is oligomycin sensitive proton channel through the membrane. Thus, F1 is attached to F0 so that its active center faces the proton channel F0. As a result of ATP hydrolysis, the protons are released into the channel, while ADP and Pi are transported back through F1 to the aqueous phase. However, in the synthesis of ATP, protons are picked up from the proton channel by phosphate, and phosphorylation of ADP occurs in the active center of F1.


synthesis of ATP by the chemiosmotic mechanism ..

The major force for ATP synthase functioning is a proton gradient and membrane potential as is the case for the other model. Proton flow, passing through proton channel in F0 located at the border between a-, c- and b 2-subunits, change pH of matrix, stroma, or cytosol to pH 7.0, and three protons are delivered to active centers. At the expense of proton gradient, transport of cations, and change of volumes of organelles take place. Membrane potential causes rotation of γ-subunit and twisting of b 2-subunits. At the expense of membrane potential, three protons, three phosphate ions are delivered to active centers. Due to electrostatic interactions nucleophilic substitution takes place, phosphoryl groups are formed, three molecules of ATP are synthesized, ATPs are released from the enzyme, and ADP molecules are loaded to active centers

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pmf is what drives ATP synthase. The force that causes a movement of the «rotor» of ATP synthase arises as a result of difference of potentials between outer and inner sides of the membrane (>220 mV) and is provided by proton flow, passing through a special channel in F0 located between subunits a and c

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During ATP synthesis, energy is, predominantly, used first, for the delivery of phosphate ions and protons to the α 3 β 3-hexamer against the energy barrier with the help of C-terminal alpha-helix of γ-subunit that acts as a lift; second, for the formation of phosphoryl groups; and third, for the release of ATP molecules from the active center of the enzyme and the loading of ADP. We suggest that sodium ions are involved in the loading of ADP and in the release of ATP from the top of the α 3 β 3-hexamer of the ATP synthase.