Monosaccharides disaccharides

The structural components encountered in E. coli are also present in lipid A of other bacterial sources. Thus, a survey of the structures analyzed shows that lipid A, in general, contain two g/wcoconfigured and pyranosidic D-hexosamine residues (2-amino-2-deoxy-D-glucose, GlcpN, or 2,3-diamino-2,3-dideoxy-D-glucose, GlcpN3N, also termed DAG (49,50)], which are present as a ) -(l — 6)-linked disaccharide (monosaccharide backbones have also been identified, but the respective lipid A lack endotoxic activity). The disaccharide is phosphorylated by one or, in most cases, two phosphate... 

Sucrose, ninhydrin reaction, effect on, 153 Sugars, see also Disaccharides Monosaccharides ... 

Disaccharides — monosaccharides (glucose and galactose from lactose fructose from other sources) Polysaccharides — glucose... 

Sugars are either mono- or disaccharides. Monosaccharides include glucose, fructose, galactose, and ribose, and differ in chemical structure. Because the chemistry of saccharides is quite complicated, we shall discuss only the most important aspects that are needed from the pol5mier chemistry point of view. Monosaccharides are the building blocks of disaccharides such as sucrose, and polysaccharides such as cellulose and starch. The chemical structure in an open form can be represented as shown in Figure 5. 2. 

Glucose and fructose (CeHijOj, monosaccharides) sucrose maltose and lactose (CiaHja n, disaccharides) starchy (CaHiflOs), a polysaccharide. 

The weights of other monosaccharides and reducing disaccharides which will reduce i ml. of this standard Fehling s solution are galactose, 0 00511 g- fructose. 0 00514 g.. mannose, 0 00431 g. lactose, 0 00678 g. maltose, 0 00807 g. 

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

Disaccharides are sugars which yield two molecules of monosaccharides upon hydrolysis. The four of greatest practical interest are ... 

Disacchandes are carbohydrates that yield two monosaccharide molecules on hydroly SIS Structurally disaccharides are glycosides m which the alkoxy group attached to the anomeric carbon is derived from a second sugar molecule... 

Disaccharide (Sections 25 1 and 25 14) A carbohydrate that yields two monosaccharide units (which may be the same or different) on hydrolysis... 

Sugar is destroyed by pH extremes, and inadequate pH control can cause significant sucrose losses in sugar mills. Sucrose is one of the most acid-labile disaccharides known (27), and its hydrolysis to invert is readily catalyzed by heat and low pH prolonged exposure converts the monosaccharides to hydroxymethyl furfural, which has appHcations for synthesis of glycols, ethers, polymers, and pharmaceuticals (16,30). The molecular mechanism that occurs during acid hydrolysis operates, albeit slowly, as high as pH 8.5 (18). 

Among the various types of sugars marketed, the mass consumption of sucrose far outweighs by volume the consumption of other products. Sucrose, also called table sugar, is a disaccharide which, upon hydrolysis, yields two monosaccharides glucose and fmctose. Various types of sugar vary in sweetness (1). 

Dextrose (D-glucose) is by far the most abundant sugar in nature. It occurs either in the monosaccharide form (free state) or in a polymeric form of anhydrodextrose units. As a monosaccharide, dextrose is present in substantial quantities in honey, fmits, and berries. As a polymer, dextrose occurs in starch, cellulose (qv), and glycogen. Sucrose is a disaccharide of dextrose and fmctose. 

Lactose is a disaccharide constituting 2-6% of milk and is known as milk sugar. It differs from maltose and cellobiose in that only one of its monosaccharide units is D-glucose. The other monosaccharide unit, the one that contributes its anomeric carbon to the glycoside bond, is D-galactose. Like cellobiose, lactose is a p-glycoside. 

Sections Disaccharides are carbohydrates in which two monosaccharides are 25.14-25.15 joined by a glycoside bond. Polysaccharides have many monosaccharide units connected through glycosidic linkages. Complete hydrolysis of disaccharides and polysaccharides cleaves the glycoside bonds, yielding the free monosaccharide components. 

Sucrose (Section 25.14) A disaccharide of glucose and fructose in which the two monosaccharides are joined at their anomeric positions. 

We saw in Section 25.6 that reaction of a monosaccharide with an alcohol yields a glycoside in which the anomeric -OH group is replaced by an -OR substituent. If the alcohol is itself a sugar, the glycosidic product is a disaccharide. 

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