Glucose, aerobic oxidation

The citric acid cycle is the final common pathway for the aerobic oxidation of carbohydrate, lipid, and protein because glucose, fatty acids, and most amino acids are metabolized to acetyl-CoA or intermediates of the cycle. It also has a central role in gluconeogenesis, lipogenesis, and interconversion of amino acids. Many of these processes occur in most tissues, but the hver is the only tissue in which all occur to a significant extent. The repercussions are therefore profound when, for example, large numbers of hepatic cells are damaged as in acute hepatitis or replaced by connective tissue (as in cirrhosis). Very few, if any, genetic abnormalities of citric acid cycle enzymes have been reported such ab-normahties would be incompatible with life or normal development. 

At room temperature and in the presence of oxygen the colloidal dispersion stabilized by glucose is less stable than the PVA stabilized ones owing to the slow glucose aerobic oxidation growth of particles from 2.7 to 3.5 nm has been observed in a few hours. 

The LbL methods have been also used to prepare spatially ordered bienzymatic electrodes, two examples are shown in Figure 2.25. In the first one, glucose is aerobically oxidized by GOx in the outer layers to produce hydrogen peroxide that is thereafter reduced by soybean peroxidase (SBP) wired to the electrode with PAH-Os [182]. This system responds both to H2O2 and to glucose, but in the... 

When animal tissues cannot be supplied with sufficient oxygen to support aerobic oxidation of the pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by the reduction of pyruvate to lactate. As mentioned earlier, some tissues and cell types (such as erythrocytes, which have no mitochondria and thus cannot oxidize pyruvate to C02) produce lactate from glucose even under aerobic conditions. The reduction of pyruvate is catalyzed by lactate dehydrogenase, which forms the l isomer of lactate at pH 7 ... 

TAs one might predict, mutations in the genes for the subunits of the PDH complex, or a dietaiy thiamine deficiency, can have severe consequences. Thiamine-deficient animals are unable to oxidize pyruvate normally. This is of particular importance to the brain, which usually obtains all its energy from the aerobic oxidation of glucose in a pathway that necessarily includes the oxidation of pyruvate. Beriberi, a disease that results from thiamine deficiency, is characterized by loss of neural function. This disease occurs primarily in populations that rely on a diet consisting mainly of white (polished) rice, which lacks the hulls in which most of the thiamine of rice is found. People who habitually consume large amounts of alcohol can also develop thiamine deficiency, because much of their dietaiy intake consists of the vitamin-free empty calories of distilled spirits. An elevated level of pyruvate in the blood is often an indicator of defects in pyruvate oxidation due to one of these causes. ... 

TABLE 16-1 Stoichiometry of Coenzyme Reduction and ATP Formation in the Aerobic Oxidation of Glucose via Glycolysis, the Pyruvate Dehydrogenase Complex Reaction, the Citric Acid Cycle, and Oxidative Phosphorylation... 

Gold NPs deposited on carbons are active and selective for mild oxidations in liquid phase although they exhibit almost no catalytic activity in the gas phase. Examples are aerobic oxidation of mono-alcohols, diols, glycerol, glucose, alkenes and alkanes. 

The GOX-B-immunosensors are potentiostated at +0.6 V vs. SCE to detect the aerobic oxidation of glucose with the concomitant production of H202. 

Fig. 4.12 Aerobic oxidation of D-glucose catalyzed by flavin-dependent glucose oxidase.

Table 9.3 Calculation of ATP yields upon complete Aerobic oxidation of Glucose.

The PEP-fructophosphotransferase system does not exist in Spirillum itersoii, Pseudomonas aeruginosa,181,182 or several other genera of aerobic, oxidative bacteria.183 The transport system for D-glucose, D-fructose, and D-mannitol is energy- and temperature-dependent, obeys saturation kinetics, and is inducible.181,182 This indicates the presence of a carrier-mediated transport-system.184 D-Fructose is transported as the free sugar, and trapped intracellularly by phosphorylation, An inducible fructokinase (EC 2.7.1.4) converts transported D-fructose into D-fructose 6-phosphate.181... 

While the rate of utilization of glucose by rat tissues is only reduced by 10% at this stage of the injury, glucose aerobic oxidation is more severely affected, being reduced by 30%. This is about the same as the reduction in total O2 consumption of the rat at this time. Unlike glucose, the oxidation of pyruvate is inhibited by some 70% after injury. 

The aerobic oxidation of glucose yields between 29.5 and 31 ATP molecules. 

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