Glucose periodic acid degradation

By contrast, acetyl CoA does not have anaplerotic effects in animal metabolism. Its carbon skeleton is completely oxidized to CO2 and is therefore no longer available for biosynthesis. Since fatty acid degradation only supplies acetyl CoA, animals are unable to convert fatty acids into glucose. During periods of hunger, it is therefore not the fat reserves that are initially drawn on, but proteins. In contrast to fatty acids, the amino acids released are able to maintain the blood glucose level (see p. 308). 

Thus, for glucose, the acid seems to slow down the more severe urea-linked degradation in the long early stage, whereas, for xylitol, urea stops the severe acid-catalyzed degradation in this period. 

Bevington and coworkers have suggested a scheme for determining the distribution of radioactive carbon in labeled n-glucose, using the degradation of D-arabino-hexose phenylosotriazole. The scheme is based on the periodate oxidation of n-ambmo-hexose phenylosotriazole and d-arabino-hexose phenylosotriazole 6-benzoate. The former gives formaldehyde from C-6, formic acid from C-4 and C-5, and 4-formyl-2-phenyl-1,2,3-triazole from C-1, C-2, and C-3. This latter aldehyde can be further... 

C. Sch5pf and H. Wild, The degradation of D-glucose to 2-formyl-D-glyceraldehyde with periodic acid, Ber., 87 (1954) 1571-1575. 

As a preparatory method, oxidation with periodic acid is of particular importance for the preparation of short-chain sugars. For example, 2,3-0-benzylidene-D-arabitol (I) consumes one mole of periodic acid and yields 2,3-0-benzylidine-D-threose (II) which can be converted to a crystalline isopropylidene derivative 226), The oxidation of aldoses by one mole of lead tetraacetate in acetic acid will cause degradation to aldoses containing one less carbon thus, D-arabinose and D-lyxose have been prepared in yields of more than 35% from D-glucose and D-galactose, respectively 227), The... 

A chemical method (41) of degrading glucose was developed to distinguish between carbon atoms 3 and 6. D-Glucose was converted to the methyl D-glucopyranoside which was then oxidized with periodic acid at room temperature to convert carbon atom 3 to formic acid. A second periodic acid oxidation of the hydrolyzed dialdehyde, which was also produced, gave carbon atom 6 as formaldehyde. 

Figure 16.11 Pattern of fuel utilisation during prolonged starvation. The major metabolic change during this period is that the rates of ketone body formation and their utilisation by the brain increases, indicated by the increased thickness of lines and arrows. Since less glucose is required by the brain, gluconeogenesis from amino acids is reduced so that protein degradation in muscle is decreased. Note thin line compared to that in Figure 16.9.

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