Disaccharides maltose

FIGURE 25.6 Molecular models of the disaccharides maltose and cellobiose. Two D-glucopyranose units are connected by a glycoside linkage between C-1 and C-4. The glycosidic bond has the a orientation in maltose and is p in cellobiose. Maltose and cellobiose are diastereomers. 

Polysaccharide (starch) Amylase Fragment polysaccharides into disaccharides (maltose) Salivary glands pancreas Mouth stomach small intestine... 

Figure 4.19 The structures of the disaccharides maltose and cellobiose, derived from the hydrolysis of starch and cellulose, respectively.

Figure 9.15 Structure of disaccharides. Maltose and cellobiose are both disaccharides which contain only glucose units, the difference in their structures lying in the way the glucose units are joined. The glycosidic linkage in maltose is afl—>4), whereas that in cellobiose is (1—>4).

Sucrose (disaccharide) Maltose (disaccharide) Raffinose (trisaccharide)... 

Enzymes are also added to catalyze the hydrolysis or saccharification of starch. Malt produced by the germination of barley grain contains the enzymes that catalyze this hydrolysis. Sometimes called diastase, the enzymes are primarily a- and 6-amylase. Glucoamylase is a pure enzyme that can now be used. Both diastase and glucoamylase hydrolyze starch polysaccharide to the disaccharide, maltose. For fuel grade ethanol production, hydrolysis takes place at temperatures ranging from about 120°F to 140°F (50°C to 60°C) for about 1 hour. The final product of hydrolysis is called a wort. Solids can be filtered from the wort before continuing. 

MOEMIm][BF4], in which 5gl/1 of glucose dissolves at 55°C (100 times faster than in acetone) [28]. The disaccharide maltose was also acylated in the presence of CaLB in [MOEMIm][BF4] [28]. 

Using conditions similar to those employed for the preparation of the polyglucoses, Mora and coworkers174 also polymerized other aldohexoses (D-galactose and D-mannose), two deoxy sugars (2-deoxy-D-ara mo-hexose and 6-deoxy-L-mannose), aldopentoses (L-arabinose, D-xylose, and D-ribose), and a disaccharide (maltose). Milder conditions were required for the deoxy sugars and the pentoses. The properties of these polymers are presented in Table IV. 

A glycoside can be formed with aliphatic alcohols, phenols, and hydroxy carboxylic acids, but the most important glycosides are those formed with other sugars. Monosaccharides are linked by glycosidic bonds to form disaccharides (fig. 12.8). For instance, the disaccharide maltose contains a glycosidic bond between the C-l of one glucose molecule and the C-4 of another. The compound is said to... 

This section will present only a short selection from the numerous reports on the conformation of disaccharides. Maltose, for example, has attracted a lot of interest with numerous papers dealing with its conformational properties of which only a few have been selected. 

The major saccharidase of the small intestine is amylase that digests starch to the disaccharide maltose and the trisaccharide maltotriose. Intestinal mucus is secreted by goblet cells, which either ooze (constitutive basal secretion) or burst as a result of stimuli. In the last mode of secretion condensed mucus gel granules can expand 500-fold within 20 ms [20]. 

As for hydrolysis of disaccharides maltose and cellobiose, the (Ha anomeric ratios are in agreement in terms of stereoelectronic effects which are, according to the... 

Starch is the food reserve of plants. It consists of two components amylose and amylopectin. Amylose consists of several thousand glucose units linked by a-glycosidic bonds between carbons 1 and 4 to form a linear polymer. Incomplete hydrolysis of amylose produces the disaccharide maltose, which also has an a-glycosidic bond. Although amylose differs from cellulose only in the stereochemistry of the glycosidic bonds between its glucose monomers, it has a very different shape and quite different physical. 

Common disaccharides—maltose from malt, lactose from milk, and sucrose, common table sugar (Section 27.12) Common polysaccharides—cellulose, starch, and glycogen (Section 27.13)... 

Figure 11.10. Maltose, a Disaccharide. Two molecules of glucose are linked by an a -1,4-glycosidic bond to form the disaccharide maltose.

Amylopectin is hydrolyzed to the single disaccharide (+)-maltose the sequence of methylation and hydrolysis yields chiefly 2,3,6-tri-O-methyl-D-glucose. Like amylose, amylopectin is made up of chains of D-glucose units, each unit joined by an alpha glycoside linkage to C-4 of the next one. However, its structure is more complex than that of amylose. 

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