Oxidative phosphorylation definition

Note also that, from a physicochemical point of view, in all schemes reflecting A/ZII-dependent transport systems on both sides of the membrane, H+ ions may be taken for a catalyst, which intensifies the proceeding of definite processes, either oxidative phosphorylation, osmotic work or other types of work. 

Limited studies have documented phytotoxic effects of usnic acid including inhibition of transpiration and oxygen evolving processes in maize and sunflower seedlings.23 Studies of mouse mitochondria have suggested that (+)-usnic acid uncouples oxidative phosphorylation at levels of 1 pM.1 However, a definitive explanation of the phytotoxicity of usnic acid had, to our knowledge, never been reported. Thus, we have attempted to determine the phytotoxic mode of action for (-)-usnic acid.33... 

In an experiment, a suspension of mitochondria provided with adequate oxygen and pyruvate, but no ADP, consumed oxygen at a very low rate. The relative states of reduction of components of the electron-transport chain were determined NAD, 100 percent coenzyme Q, 40 percent cytochrome b, 38 percent cytochrome c, 14 percent and cytochrome a, 0 percent. How could these data allow definition of the sites of oxidative phosphorylation ... 

The matrix of the phenomenological coefficients must be positive definite for example, for a two-flow system, we have L0 > 0, Ip >0, and Z/.p Z,pZpo > 0.1,0 shows the influence of substrate availability on oxygen consumption (flow), and Ip is the feedback of the phosphate potential on ATP production (flow). The cross-coupling coefficient Iop shows the phosphate influence on oxygen flow, while Zpo shows the substrate dependency of ATP production. Experiments show that Onsagers s reciprocal relations hold for oxidative phosphorylation, and we have Iop = Zpo. 

There is evidence that long-term phosphine exposure by individuals involved in the application of pesticides resulted in chromosome damage. Chronic exposure to very low levels of phosphine may result in altered motor, visual, and speech skills. Neither aluminum phosphide nor phosphine gas exhibit carcinogenicity in humans, or result in reproductive or developmental effects. Although definitive evidence is lacking, it is assumed that phospine is an in vivo inhibitor of oxidative phosphorylation. 

A system with definite inside and outside compartments (closed vesicles) is essential for oxidative phosphorylation. The process does not occur in soluble preparations or in membrane fragments without compartmentalization. 

The mechanism of action of the phenothiazines is still not definitely known. They tend to block important effector substances such as acetylcholine, epinephrine, and histamine. The phenothiazines produce uncoupling of phosphorylation from oxidation. They appear to act at all steps along the electron transport chain. Cytochrome oxidase, succinoxidase, and adenosine triphosphatase are inhibited. Some data indicate that the phenothiazines may decrease the permeability of storage granules for brain amines. 

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