Glucose direct oxidation

Many dehydrogenase enzymes catalyze oxidation/reduction reactions with the aid of nicotinamide cofactors. The electrochemical oxidation of nicotinamide adeniiw dinucleotide, NADH, has been studied in depthThe direct oxidation of NADH has been used to determine concentration of ethanol i s-isv, i62) lactate 157,160,162,163) pyTuvate 1 ), glucose-6-phosphate lactate dehydrogenase 159,161) alanine The direct oxidation often entails such complications as electrode surface pretreatment, interferences due to electrode operation at very positive potentials, and electrode fouling due to adsorption. Subsequent reaction of the NADH with peroxidase allows quantitation via the well established Clark electrode. 

Bayne, Fewster and Mitchell16 prepared VII by the method of Stacey and Turton, and recorded physical properties closely agreeing with those reported by Maurer.66 The compound was clearly related to D-glucosone, prepared from D-glucose phenylosazone and by direct oxidation, since, on treatment with dry acetone containing concentrated sulfuric acid, it gave crystalline tri-0-isopropylidene-(2-hydroxy-D-arabmo-hexose). 7... 

In the preparation of D-glucosone by the direct oxidation of D-glucose, D-fructose, or D-mannose by such reagents as that of Fenton,37 cupric acetate,16- 46- 46 selenious acid,16-61 etc., the degree of oxidation must be carefully controlled if the osone, which is the first product, is to be the main product of the reaction. The nature and mechanism of formation of the products of further oxidation of D-glucosone are discussed on p. 68. 

Hemolytic anemia results from decreased RBC survival time due to destruction in the spleen or circulation. The most common etiologies are RBC membrane defects (e.g., hereditary spherocytosis), altered Hb solubility or stability (e.g., sickle cell anemia [see Chap. 34] and thalassemias), and changes in intracellular metabolism (e.g., glucose-6-phosphate dehydrogenase deficiency). Some drugs cause direct oxidative damage to RBCs (see Appendix 3). 

The reactions in Eqs. (10) and (11) indicate the links with glucose metabolism, the former to the direct oxidative pathway, the latter to the glycolytic route. The essential link in the reduction of MHb is the generation of reduced pyridine nucleotides (B14, R12, S10). The... 

D7. Dickens, F., and Glock, G. E., Direct oxidation of glucose-6-phosphate by animal tissues. Nature 166, 33 (1950). 

Recently, a novel microbial fuel cell harvesting energy from the marine sediment—seawater interface has been reported. Also, a novel photosynthetic biofuel cell that is a hybrid between a microbial and enzymatic biofuel cell has been reported for the very first time. More recently, reports of an unconventional biomass-fueled ceramic fuel cell can also be found in the literature. A new concept of Gastrobots —hybrid robots that utilize operational power derived from microbial fuel cells—has been introduced. Finally, the generation of electrical power by direct oxidation of glucose was demonstrated in mediatorless microbial fuel cells, which produced currents up to 3 fiA/cm at unknown cell voltage. ... 

The idea is then that insulin resistance at the adipocytes gives a weaker inhibition of the HSL, so more FAs are released. This may very well be the case, but it cannot last for long, because then the fat stores would be emptied and the typical type 2 patient is obese. Instead, a new theory is emerging. As previously mentioned, it seems that adipocytes can create considerable amounts of fat from glucose [63]. This fat can be stored or it can be oxidized. In the latter case, another so-called futile process is active. Instead of oxidizing the glucose directly, it is first converted into fat and then oxidized as fat. 

Chaudhuri, S., Lovley, D. (2003). Electricity generation by direct oxidation of glucose in mediatorless microbial fuel cells. Nature Biotechnology 21,1229-1232. 

A related oxidation reaction is catalyzed by glucose-6-phosphate dehydrogenase, the enzyme that originally attracted Warburg s attention and led to the discovery of NADP. The subsfrafe, the hemiacetal ring form of glucose, is oxidized fo a lactone which is then hydrolyzed to 6-phosphogluconate (Eq. 15-10). This oxidation of an aldehyde to a carboxylic acid is not linked directly to ATP synthesis as in Fig. 15-6. 

---