Metabolism of amino sugars

Figure 20-7. Summary of the interrelationships in metabolism of amino sugars. (At asterisk Analogous to UDPGIc.) Other purine or pyrimidine nucleotides may be similarly linked to sugars or amino sugars. Examples are thymidine diphosphate (TDP)-glucosamine and TDP-N-acetylglucosamine.

W4. Warren, L., The biosynthesis and metabolism of amino sugars and amino sugar-containing heterosaccharides. In Glycoproteins (A. Gottschalk, ed.), 2nd ed.. Part B, pp. 1097-1126. Elsevier, Amsterdam, 1972. 

The other example presented of a non-scrambled distribution of isotopes involves the synthesis of collagen. For a mature animal at steady state, we might expect extensive atomic scrambling in the sense that most of the non-essential amino acid content of this protein (78% of its carbon atoms) can be synthesized from the general pool of glycogenic substrates that arise from metabolism of all sugars and fats, although the pathway from fats is restricted... 

Ammonia lyases in their natural role are involved in the metabolism of amino acids and also play a role in, for instance, the degradation of amino sugars, but only a limited amount of these enzymes have been characterized biochemically. Application of a broad range of different ammonia and lyases in organic chemical synthesis on an industrial scale has thus far not occurred, which is due to both their limited commercial availability and their lack of stability under process conditions. Exceptions are the commercially applied aspartase, which is an ammonia lyase that is utilized for the synthesis of L-aspartic acid from fumaric acid, and phenylalanine lyase. The latter is an example of a commercial application of an ammonia lyase in a process for the production of L-phenylalanine and more importantly L-phenylalanine derivatives. 

See also Fructose, Biosynthesis of Amino Sugars, Fructose Metabolism, Glucosamine-6-Phosphate... 

The incorporation of amino-sugar and sulphate into low-sulphate content chondroitin 4-sulphate in rat blood shows a high metabolic rate which is quite different from that of tissue glycosaminoglycans. ... 

The physiological function of higher alcohol production by yeasts is not clear. It may be a simple waste of sugars, a detoxification process of the intracellular medium, or a means of regulating the metabolism of amino acids. 

FRET-based nanosensors have been successfully used to monitor steady state levels of metabolites, nutrients, and ions in mammalian cells [74, 87], Recently FRET-based glucose, sucrose, and amino acid nanosensors have been developed to study the metabolism of glucose, sucrose, and amino acid uptake and metabolism in plant cells [80,89, 91]. The enormous potential of these nanosensors will be crucial for understanding ion (e.g., calcium), metabolite (e.g., sugars), hormone (e.g., auxins, gibberellins etc.), and nutrient (e.g., nitrogen, potassium, phosphorus) requirements and homeostasis in living plant tissues. 

R. W. Jeanloz andE. A. Balazs, The Amino Sugars (1966) Academic Press, New York, 1A Distribution and Biological Roles, 591 pp, Vol. 2A Chemistry of the Amino Sugars, 827 pp, Vol. 2B Metabolism and Interactions. 

The relationship, if any, between the secondary metabolism of L-phenylalanine and carbohydrate degradation during brown-rot wood decay processes has not yet been determined. However, we suspect that the secondary metabolism of this aromatic amino-acid plays an important role in converting monomeric sugars to nitrogen-free metabolites (Shimada, M., and Takahashi, M., In Handbook of Wood and Cellulosic Materials Hon,... 

When soybean leaves and pine needles were exposed to ozone, there was an initial decrease in the levels of soluble sugars followed by a subsequent increase. Ozone exposure also caused a decrease in the activity of the glycolytic pathway and the decrease in the activity was reflected in a lowered rate of nitrate reduction. Amino acids and protein also accumulated in soybean leaves following exposure. Ozone increased the activities of enzymes involved in phenol metabolism (phenylalanine ammonia lyase and polyphenoloxidase). There was also an increase in the levels of total phenols. Leachates from fescue leaves exposed to ozone inhibited nodulation. 

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