Glucose, total oxidation

The effect which nutrient discharges have on the dissolved oxygen of a stream is best demonstrated by reference to a simple organic molecule. If the total oxidation of glucose to carbon dioxide and water is considered (equation 10.1), one part by weight of glucose would require 1.06 parts of oxygen for complete oxidation. 

The theoretical factor for total oxidation of glucose is 7.5 mg of glucose per meq of dichromate. For total oxidation of cellulose, the factor is 6.75 mg cellulose per meq of cellulose. As indicated in TAPPI T 235, the actual oxidation is not quite theoretical and is given as 6.85 mg cellulose per meq of dichromate. Pentosans and paper sizing materials give different oxidation factors. 

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. 

Synthesis from o-glucose Total syntheses of (-l-)-valyldetoxinine (14) and (—)-detoxin Di (7) were achieved from diacetone D-glucose (Schemes 1 and 2). ° The diacetone D-glucose was oxidized with pyridinium chlorochromate and the resulting ketone... 

The information given to this point about glycolysis, the citric acid cycle, and the electron transport chain almost makes it possible to calculate the ATP yield from the total oxidation of 1 mol of glucose. However, one more factor must be considered. NADH produced in the cytoplasm during glycolysis does not pass through the mitochondrial membrane to the site of the electron transport chain. Brain and muscle cells employ a transport mechanism... 

Glucose Glucose is also a major biomass component that potentially possesses a large energy density, theoretically 4430Wh/kg based on a thermodynamic calculation for total oxidation to CO2 via a 24-electron transfer (Eq. (6.8)). 

In the total oxidation of glucose to CO2 and water, six CO2 are released and six O2 are reduced to water. For each pyruvate oxidized, four NADH and one FADH2 are generated. Since two molecules of pyruvate are derived by means of glycolysis from one molecule of glucose, a total of eight NADH and two FADH2 are formed by pyruvate oxidation. Four electrons are required for the reduction of O2 to two molecules of H2O. Thus, pyruvate oxidation accounts for the reduction of five of the six molecules of... 

All six carbons of glucose are liberated as CO2, and a total of four molecules of ATP are formed thus far in substrate-level phosphorylations. The 12 reduced coenzymes produced up to this point can eventually produce a maximum of 34 molecules of ATP in the electron transport and oxidative phosphorylation pathways. A stoichiometric relationship for these subsequent processes is 1... 

Because the 2 NADH formed in glycolysis are transported by the glycerol phosphate shuttle in this case, they each yield only 1.5 ATP, as already described. On the other hand, if these 2 NADH take part in the malate-aspartate shuttle, each yields 2.5 ATP, giving a total (in this case) of 32 ATP formed per glucose oxidized. Most of the ATP—26 out of 30 or 28 out of 32—is produced by oxidative phosphorylation only 4 ATP molecules result from direct synthesis during glycolysis and the TCA cycle. 

ATP synthase reaction has been calculated as approximately 51.6 kJ. It follows that the total energy captured in ATP per mole of glucose oxidized is 1961 kJ, or approximately 68% of the energy of combustion. Most of the ATP is formed by oxidative phosphorylation resulting from the reoxidation of reduced coenzymes by the respiratory chain. The remainder is formed by substrate-level phosphorylation (Table 17—1). 

Williams [176] has studied the rate of oxidation of C-labelled glucose in seawater by persulfate. After the oxidation, carbon dioxide was blown off and residual activity was measured. For glucose concentrations of 2000, 200, and 20 xg/l, residual radioactivities (as percentage of total original radioactivity) were 0.04, 0.05, and 0.025, respectively, showing that biochemical compounds are extensively oxidised by persulfate. With the exception of change of temperature, modifications of conditions had little or no effect. Oxidation for 2.5 h at 100 °C was the most efficient. 

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