Hydrogen ion gradient

Figure 11.8 Experiments to demonstrate the maximum achievable concentration factor. Membrane, microporous Celgard 2400/LIX 64N feed, pH 2.5, copper ion concentration, 0 or 100 ppm product, pH 1.0, 9.3 wt% copper [9]. The concentration in the feed solution moves to a plateau value of 40 ppm at which the copper concentration gradient across the membrane is balanced by the hydrogen ion gradient in the other direction...

Cotransporters use the sodium or hydrogen ion gradient to drive transport of a substrate. Many cotransporters have been described, cloned, sequenced, and expressed. The sodium-glucose cotransporter just described is one of these. 

C. Uncoupling proteins allowing dissipation of the mitochondrial hydrogen ion gradient releasing energy as heat... 

Oxidative phosphorylation The process by which adenosine triphosphate (ATP) is synthesized from a hydrogen ion gradient across the mitochondrial inner membrane. The hydrogen ion gradient is formed by the action of protein complexes in the mitochondrial membrane that sequentially transfer electrons from the rednced cofactors nicotinamide adenine dinucleotide (NADH) and FADH to molecnlar oxygen. Movement of hydrogen ions back into the mitochondrion via ATP synthase drives the synthesis of ATP. 

The third aerobic respiration stage takes place at the mitochondrial membrane, and is called electron transport phosphorylation. A hydrogen ion gradient is established and H+ flow drives formation of ATP from ADR Oxygen serves as the ultimate electron sink and produces water as a result. This stage yields 32 ATP molecules. 

A model of the ATP synthase, the effector of the chemiosmotic mechanism. A potential and a hydrogen ion gradient is created across the inner membrane of mitochondria, bacteria, and chloroplasts by redox reactions. The energy of this proton motive force is translated into ATP synthesis by rotation of the cluster of c subunits of the F , and this rotation is transmitted via the y stalk to the a-B trimers of the F, complex. The catalytic complex contains three a-6 trimers that rotate with transmission of hydronium ions inward through the c subunit complex of the Fo sector. The two b subunits tether the a-6 trimers via the 6 subunit, and the a subunit is fixed, allowing rotation of the c complex, thus rotating the y stalk. 

It can be predicted [114-115] that a pumping effect similar to the preceding one can be produced with the two sequential enzymes mixed together in one layer if their respective activities are different functions of substrate concentration or, more generally, if one of them is inhibited (or not activated) in the first part of the membrane and the other one in the other part. For the sake of simplicity, this can be illustrated with a hydrogen ion gradient and two enzymes of different optimal pH, When the hydrogen... 

Active Hydrogen-Ion-Gradient Amplificator (An Extension of the Law of Space-Oscillatory Stationary-State Profiles ) [114-115]... 

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