Glycerol glucose synthesized from

Figure 32-3. Schematic representation of fuel mobilization during fasting. Catabolism of muscle proteins provides alanine for gluconeogenesis and glutamine for utilization by the gut and kidney, while branched chain amino acids are primarily oxidized within the muscle. Breakdown of adipocyte triacylglycerols provides glycerol and free fatty acids (not shown) the free fatty acids provide fuel for liver, muscle and most other peripheral tissues. The liver utilizes both alanine and glycerol to synthesize glucose which is required for the brain and for red blood cells (not shown). Adapted from Besser and Thirner (2002).

After a meal, triacylglycerols are stored in adipose cells. They are synthesized from fatty adds (derived by the action of lipoprotein lipase on chylomicrons and VLDL) and from a glycerol moiety (derived from glucose). 

Fructose-l,6-diphosphate (FDP) may also be converted into dihydroxyacetone phosphate (DHAP), which is also synthesized from glyceraldehyde-3-phosphate (GAP). The dihydroxyacetone phosphate (DHAP), thus obtained, is converted into glycerol-3-phosphate (G-3-P), in the presence of cytosolic NADH. The latter gives away one phosphate radical to ADP to generate ATP and glycerol (Chart 1). Thus in the above process, one mole of glucose is converted into two moles of pyruvate with a net gain of two moles of ATP [1],... 

What fraction of the glucose that is synthesized from triglyceride-derived glycerol occurs during early starvation ... 

Glucose can be synthesized from noncarbohydrate materials in a process called gluconeogenesis. When carbohydrate intake is low and when glycogen stores are depleted, the carbon skeletons of lactate, glycerol (derived from the hydrolysis of fats), and certain amino acids are used to synthesize pyruvate, which is then converted to glucose ... 

Gluconeogenesis The processes by which glucose is synthesized from noncarbohydrate precursors such as glycerol, lactate, some amino acids, and (in plants) acetyl-CoA. 

The monomers used in the polycondensation reaction for the production of poly(alkylene dicarboxylate)s are basically from petrochemical sources. However, some of them can be obtained from renewable sources. For example, 1,3-propanediol can be produced by fermentation of glycerol, which is a by-product from biodiesel or plant oil production. Succinic acid can be synthesized from glucose or whey by bacterial fermentation in very high yields. ... 

Virtually all pseudo commodity and commodity chemicals as well as most fine chemicals are synthesized from petroleum feedstocks. It has been estimated that 98% of all chemicals produced in the United States in excess of 2 x 10 kg are synthesized from petroleum and natural gas. By contrast, chemicals isolated as natural products from plants or produced by microbes from carbohydrate feedstocks are typically restricted to ultrafme chemicals and a relatively few fine chemicals. The goal of our research effort is to ascertain how the widest possible spectrum of commodity, pseudo commodity, fine, and ultrafine chemicals can be synthesized from polyol starting materials such as d-glucose, d-xylose, 1-arabinose, and glycerol. These starting materials, in turn, are derived from renewable feedstocks derived from plants such as starch, hemicellulose, cellulose, and oils. A key feature of these conversions is the use of recombinant microbes as synthetic catalysts. 

Gluconeogenesis is the sequence of reactions by which glucose or glycogen is synthesized from a wide variety of non-carbohydrate precursors. The predominant starting materials are lactate, glycerol, most amino acids (Section 16.3) and tricar-boxylate cycle intermediates. The interrelationships of these pathways are shown in Figure I l.l. 

Higher organisms are not able to synthesize glucose from acetyl CoA but must instead use one of the three-carbon precursors lactate, glycerol, or alanine, all of which are readily converted into pyruvate. 

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