Monosaccharides fructose

How does the chemical structure of the monosaccharide glucose differ from that of the monosaccharide fructose ... 

Membranes in the third group contain pores with diameters between 5 A and 10 A and are intermediate between truly microporous and truly solution-diffusion membranes. For example, nanofiltration membranes are intermediate between ultrafiltration membranes and reverse osmosis membranes. These membranes have high rejections for the di- and trisaccharides sucrose and raffi-nose with molecular diameters of 10-13 A, but freely pass the monosaccharide fructose with a molecular diameter of about 5-6 A. 

Fig. 11 -15 The conversion of the monosaccharides fructose and mannose into the glycolytic intermediate fructose 6-phosphate.

Fig. 11-17 The conversion of the monosaccharide fructose into the glycolytic intermediates dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

In addition to using numerical prefixes in the general names of sugars to indicate how many carbon atoms are present, we often use the prefixes keto- and aldo- to indicate whether the sugar is a ketone or an aldehyde. For example, the monosaccharide fructose is frequently called a ketohexose to emphasize that it contains six carbons as well as the ketone functional group. For each of the monosaccharides shown in Table 22.8 classify the sugars as aldohexoses, aldopentoses, ketohexoses, or ketopentoses. 

The first step is searching out a flower to pick up some nectar. Nectar is a mixture of sugar and water. Specifically, the sugar in nectar used to make honey is sucrose, a disaccharide (see Biochemistry ). A honeybee produces enzymes in its body that Ctm break down the sucrose into monosaccharides, fructose, and glucose as well as gluconic acid. These sugars are the primary constituents of honey. Most of the water evaporates, which is what makes honey so viscous and sticky. 

Carbohydrates Carbohydrates are a major source of energy for humans and are present in all foods (grains, vegetables, fruits, and milk), and vary in form from simple monosaccharides (fructose, glucose, galactose, sorbitol) to oligosaccharides (maltose, sucrose, lactose, raffinose, stachyose, ver-bascose), and more complex polysaccharides (starch, cellulose, etc.). 

Maltose and sucrose are examples of disaccharides. On hydrolysis, 1 mol of maltose yields 2 mol of the monosaccharide glucose sucrose undergoes hydrolysis to yield 1 mol of glucose and 1 mol of the monosaccharide fructose. Starch and cellulose are examples of polysaccharides both are glucose polymers. Hydrolysis of either yields a large number of glucose units. The following shows these hydrolyses in a schematic way ... 

Anomers also appear in cyclic form as five-membered rings, for instance in the monosaccharides fructose and ribose. These cyclic molecules are named furanoses because of their similarities to the cyclic ether furan. Starting from D-fructose and D-ribose, the cyclization yields anomers a- and p-D-fructofuranose, as well as a-and P-D-ribofuranose, respectively. 

The supramolecular systems with nanosilica, proteins, and monosugars or disaccharides can possess a high bioactivity and be used in bionanocomposites perspective for biotechnology and medicine (Devis and Robinson 2002, Chuiko 2003). It was shown that composites on the basis of nanosilica, BSA, polyol (sorbitol, xylitol), or monosaccharides (fructose, glucose) in wide range of concentrations can stimulate activity and prolong lifetime of cells after their cryopreservation. 

Hlie chemistry of the conversion of the disaccharide sucrose ([a]o = +66.5) to the monosaccharide fructose ([a]D = -92.4) and an equilibrium mixture of a-D-glucopyranose (a-D-glucose) and its anomer, (i-D-glucopyranose (p-D-glucose) ([ajo = +52.7 for the mixture), the structures of which were unknown at the time, will be discussed in Chapter 11. The positive rotation of the mixture of glucose epimers is less than the high negative rotation of fructose. 

In 2008, Cipolla and Nicotra, focused on the synthesis of conformationally constrained l,4-benzodiazepine-2,5-diones (97-101), containing both a monosaccharide, fructose and a proline moiety (Fig. 28). ° The D-proline moiely is connected to fructose through a spiro junction that provides a high conformational rigidity. 

All sugars with free reducing groups are very reactive. In mildly acidic solutions monosaccharides are stable, while disaccharides hydrolyze to yield monosaccharides. Fructose is maximally stable at pH 3.3 glucose at pH 4.0. At lower pH s dehydration reactions prevail, while the Lo-bry de Bruyn-van Ekenstein rearrangement oc-... 

Various papers have recently been published concerning the liquid-phase titration of acid solids, such as acidic polymeric resins [107-109]. Example is here presented on the study of the intrinsic and effective acidities of two catalysts based on niobium niobium oxide (NBO) and niobium phosphate (NBP) [110] which found application in reaction of acid transformation of monosaccharides (fructose, glucose, in particular) to useful chemicals, like 5-hydroxymethyl-2-furaldehyde (HMF) [111, 112]. 

The simplest carbohydrates are the monosaccharides. A monosaccharide cannot be split or hydrolyzed into smaller carbohydrates. One of the most common carbohydrates, glucose, C6H12O6, is a monosaccharide. A disaccharide consists of two monosaccharide units joined together, which can be split into two monosaccharide units. For example, ordinary table sugar, sucrose, C12H22O11, is a disaccharide that can be split by water (hydrolysis) in the presence of an acid or an enzyme to give one molecule of glucose and one molecule of another monosaccharide, fructose. 

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