Oxidation products of glucose

Figure 9.11 Oxidation products of glucose. Gluconic acid is an aldonic acid formed when the aldehyde group is oxidized. Glucuronic acid, a uronic acid, is a result of oxidation of the primary alcohol group. When both the aldehyde and the primary alcohol groups are oxidized, glucaric acid is formed, which is an aldaric acid.

Aldaric acid (Saccharic acid) 6 Glucaric acid Oxidation product of glucose... 

However, the papers published before the 1960s should be considered critically, because the reliable analytical specification of the various oxidation products of glucose was only possible after introduction of high performance liquid chromatography (HPLC) and ion-exchange chromatography (IC). 

Evidence has been presented that the primary oxidation product of glucose-6-phosphate is the 5-lactone of 6-phosphogluconic acid (Fig. 9). This product was observed to react rapidly with hydroxylamine to form a hydroxamic acid in a manner analogous to the reactivity of 5-glucono-... 

Lactate, a product of glucose catabolism in oxygen-starved muscles, can be converted into pyruvate by oxidation. What coenzyme do you think is needed Write the equation in the normal biochemical format using a curved arrow. 

Figure 7-10. Coupled enzyme assay for hexokinase activity. The production of glucose 6-phosphate by hexokinase is coupled to the oxidation of this product by glucose-6-phosphate dehydrogenase in the presence of added enzyme and NADP". When an excess of glucose-6-phosphate dehydrogenase is present, the rate of formation of NADPH, which can be measured at 340 nm, is governed by the rate of formation of glucose 6-phosphate by hexokinase.

The first enzyme biosensor was a glucose sensor reported by Clark in 1962 [194], This biosensor measured the product of glucose oxidation by GOD using an electrode which was a remarkable achievement even though the enzyme was not immobilized on the electrode. Updark and Hicks have developed an improved enzyme sensor using enzyme immobilization [194], The sensor combined the membrane-immobilized GOD with an oxygen electrode, and oxygen measurements were carried out before and after the enzyme reaction. Their report showed the importance of biomaterial immobilization to enhance the stability of a biosensor. 

C8. Cori, O., and Lipmann, F., The primary oxidation product of enzymatic glucose-6-phosphate oxidation. ]. Biol. Chem. 194, 417-425 (1952). 

The increased sensitivity of the electrodes coated with the hydrophobin layer is also appealing. The hydrophobin-modified electrodes allow H2O2, the product of glucose oxidation, to be detected at a concentration of 0.2 mM. This level is significantly lower than the detection limit of the bare electrode, which is 0.9 mM. The authors attribute the increase in electrode performance to the local accumulation of H202 at the electrode surface or a possible decrease in current in the presence of the hydrophobin layer. 

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