Sugars carbonation

Furfural is derived from biomass by a process in which the hemiceUulose fraction is broken down into monomeric 5-carbon sugar units which then are dehydrated to form furfural. 

Phenylalanine- and Tyrosine-Derived Alkaloids. Carbohydrate metaboHsm leads via a seven-carbon sugar, ie, a heptulose, derivative to shikimic acid [138-59-0] (57), C H qO, which leads in turn to prephenic acid [126-49-8] (58), (43). 

Glucose A 6-carbon sugar molecule, which is the building block of natural substances like cellulose, starch, dextrans, xanthan, and some other biopolymers and used as a basic energy source by the cells of most organisms. 

P, the seven-carbon sugar serving as the transketolase substrate. Likewise, phosphoribulose kinase carries out the unique plant function of providing RuBP from Ru-5-P (reaction 15). The net conversion accounts for the fixation of six equivalents of carbon dioxide into one hexose at the expense of 18 ATP and 12 NADPH. 

Animal cells obtain much of their energy from the breakdown (catabolism) of the six-carbon sugar glucose (C(,H, 0 ). The overall reaction for the catabolism of glucose is ... 

Pyrrole, the simplest five-membered unsaturated heterocyclic amine, is obtained commercially by treatment of furan with ammonia over an alumina catalyst at 400 °C. Furan, the oxygen-containing analog of pyrrole, is obtained by acid-catalyzed dehydration of the five-carbon sugars found in oat hulls and... 

Aldotetroses are four-carbon sugars with two chirality centers and an aldehyde carbonyl group. Thus, there are 22 = 4 possible stereoisomeric aldotetroses, or two d,l pairs of enantiomers named erythrose and threose. 

You will notice that in equation (9) each molecule of six-carbon sugar gave two molecules of the three-carbon compound, glyceraldehyde. Thus, each molecule of glucose gives two COs and two ethanol molecules. 

The KDO aldolase (KdoA, EC 4.1.2.23) is involved in the catabolism of the eight-carbon sugar d-KDO, which is reversibly degraded to D-arabinose (15) and pyruvate (Figure 10.10). The enzyme has been partially purified from bacterial sources and studied for synthetic applications [71,74]. It seems that the KdoA, similar to... 

Flgure10.23 Sialyl Lewis -related selectin inhibitorandfluorogenicscreening compound for transketolase prepared using enzymatic aldolization, and multienzymatic oxidation-aldolization strategy for the synthesis of bicyclic higher carbon sugars. 

Such aldolase-catalyzed bidirectional chain elongation ( tandem aldolization) of simple, readily available dialdehydes has been developed into an efficient method for the generation of higher carbon sugars (e.g. (87)/(89)) by simple one-pot operations (Figure 10.32) [126,156]. The choice offuranoid (87) or pyranoid (89) nature of the products can be determined by a suitable hydroxyl substitution pattern in a corresponding cycloolefinic precursor (86) versus (88)). The overall specific substitution... 

F g- 3-3 The biochemical pathway of glycolysis, which obtains energy from the breakdown of 6-carbon sugars to a pair of 3-carbon pyruvate molecules. Enzymes at each reaction in the sequence are in italics. The energy generated is stored in the form of ATP (see Fig. 3-2). 

Fig. 3-11 Carbohydrates in (a) 3-, 5-, and 6-carbon sugars (monosaccharides), (b) oligosaccharides, and (c) polysaccharides. (Reprinted with permission from W. K. Purves and G. H. Orians, "Life The Science of Biology," pp. 63-81, Copyright 1987 by Sinauer Associates, Inc., Simderland, MA.)...

Derivatives of trioses, tetroses, and pentoses and of a seven-carbon sugar (sedohepmlose) are formed as meta-bohc intermediates in glycolysis and the pentose phosphate pathway. Pentoses are important in nucleotides. 

V-Acetylneuraminic acid is a common group in glycoproteins, and it contains both the amide and carboxyl chromophores. As shown in formula 11, this nine-carbon sugar derivative has an equatorial amido group on C-5 and both a hydroxyl group and a carboxyl group on the anomeric carbon atom. 

The six-carbon sugar a-galactose is identical to a-glucose except at carbon atom number 4, where the orientations are different. Draw the molecular structure of a-galactose. Simplify the stmcture by using flat rings rather than the true three-dimensional forms. 

C13-0016. The six-carbon sugar j6-mannose is identical to a-glucose except at carbon atoms in... 

C13-0018. Gulose is a six-carbon sugar that differs from glucose in two positions. In gulose the hydroxyl... 

C13-0064. The six-carbon sugar talose differs from glucose in the orientations of the hydroxyl groups at the 2 and 4 positions. Draw the structure of a-talose. 

C13-0065. The five-carbon sugar ribose can form a six-membered ring, ribop Tanose, that differs from... 

C. S. Hudson, The Fischer Cyanohydrin Synthesis and the Configurations of Higher-carbon Sugars and... 

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