Electrogenerative Synthesis

Electrogenerative synthesis, 1377 Electrogrowth of metals on electrodes, 1293 see also Electrodeposition Electrokinetic potential, 1069... 

One has synthesized anew organic compound, a useful one, but at the same time there is a by-product, electricity. The electrogenerative synthesis of dichlorethylene has been known for several years. One might consider one of the most needed and best-known chemical syntheses, the ammonia synthesis, an exothermic reaction with a heat of reaction of46.38 kJ. 

The difference in the hydrogen ion electrochemical potential, formed in bacteria similarly as in mitochondria, can be used not only for synthesis of ATP but also for the electrogenic (connected with net charge transfer) symport of sugars and amino acids, for the electroneutral symport of some anions and for the sodium ion/hydrogen ion antiport, which, for example, maintains a low Na+ activity in the cells of the bacterium Escherichia coli. 

It is worth noting that no electrogenerative process6 leading to organic synthesis on an industrial scale has as yet been publicized. Eventually such processes may need a substantial section to themselves in an electrochemistry text. 

In order to explain the Na stimulation of ATP synthesis driven by a diffusion potential the presence of a Na /H antiporter was proposed [175]. In this artificial system the acidification of the cytoplasm, which occurs in response to electrogenic potassium efflux, could be prevented by the antiporter. Subsequently, Na /H antiporter activity has been demonstrated in both Methanobacterium thermoautotrophicum [176] and in Methanosarcina harden [108]. An important result of these studies was that the Na /H antiporter could be inhibited by amiloride and harmaline, which have been described as inhibitors of eucaryotic Na" /H" antiporters [177]. Using these inhibitors it has been shown that an active antiporter is essential for methanogenesis from H2/CO2 [176,178]. The antiporter also accepts Li instead of Na, since Li stimulates CH4 formation from H2/CO2 in the absence of Na [176]. In subsequent studies the use of amiloride and the more potent derivative ethyl-isopropylamiloride permitted the discrimination of primary and secondary Na potentials generated in partial reactions of the CO2 reduction pathway. 

Translocation systems of the inner mitochondrial membrane are listed in Table 14-5. Anion translocators are responsible for electroneutral movement of dicarboxylates, tricarboxylates, a-ketoglutarate, glutamate, pyruvate, and inorganic phosphate. Specific electrogenic translocator systems exchange ATP for ADP, and glutamate for aspartate, across the membrane. The metabolic function of the translocators is to provide appropriate substrates (e.g., pyruvate and fatty acids) for mitochondrial oxidation that is coupled to ATP synthesis from ADP and Pj. 

A representation of the key experiment proving the chemiosmotic hypothesis. At the bottom is the lightactivated electrogenic proton pump, bacterial rhodopsin, and on the top the F,Fo ATP synthase. When light is shone on the vesicles coreconstituted with these two pumps in the presence of ADP and inorganic phosphate (Pi), ATP synthesis was observed. The only linkage between the two sets of structures is the electrochemical gradient of protons induced by illumination. 

Figure 1. The general mechanism for ATP synthesis by aerobes and microaerobhiles. The environmental pH that is tolerated is pH 4 to 7. This pH is the same as that found in the periplasmic space unless there are specialized mechanisms for pH regulation such as urease. Over the range of pH from 4 to 7, various substrates are oxided via a series of electron acceptors which in turn are reoxidized by oriented redox complexes so that protons are exported electrogenically across the cytoplasmic membrane. This generates an interior negative potential and an inward pH gradient to provide the proton motive force for aerobic ATP S3mthesis and H gradient linked uptake or export of ions or solutes.

The chemical synthesis of anandamide confirmed this structural identification, and allowed Mechoulam, Devane and their colleagues to determine its pharmacological properties. In vitro and in vivo tests showed a great similarity of effects between anandamide and cannabinoid drugs. Anandamide reduced the electrogenic contraction of mouse vas deferens and, most importantly, closely mimicked the behavioral responses induced by... 

In addition, GABA synthesis is associated with ATP production by coupling electrogenic antiport with glutamate decarboxylation (De Biase and Pennacchietti 2012). 

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