Cellobiose mutarotation

Mutarotation of Hydrolysis Products by Ex-1. The mutarotation of hydrolysis products from cellopentaitol by Ex-1 was investigated. For comparison those by S-l and F-l were observed. As shown in Figure 20, the mutarotation of hydrolysis products by Ex-1 (exclusively G2) increases, indicating that products are released in the / -cellobiose configuration. Entirely similar results were observed for the hydrolysis products by S-l and F-l (a mixture of Gi, G2, and reduced G3 in different proportion for each reaction mixture). Therefore, these cellulase components belong to the same group, as far as the mutarotation pattern is concerned. 

Like cellobiose, maltose has a free hemiacetal ring (on the right). This hemiacetal is in equilibrium with its open-chain form, and it mutarotates and can exist in either the a or jS anomeric form. Because maltose exists in equilibrium with an open-chain aldehyde, it reduces Tollens reagent, and maltose is a reducing sugar. 

Carbon monoxide, evolution from cellulose on beating, 428, 429 Carbonylation, of alkyl balides, 61 Carbonyl groups, formation from cellulose on heating, 426, 428, 435 Carboxyl groups, formation from cellulose on beating, 426, 427, 435 Cardenolides, synthesis of 1,2-cis-, 267 Cellobiose, /8-, mutarotation of, 23 Cellulase, 376 Cellulose... 

Maltose and cellobiose are both reducing sugars because the anomeric carbons on the right-hand glucopyranose units have hemiacetal groups and are in equilibrium with aldehyde forms. For a similar reason, both maltose and cellobiose e.xhibit mutarotation of a and p anomers of the glucopyranose unit on the right. 

Problem 18.27. Show the loss of water between OH groups of two glucose molecules to form cellobiose. Mark each hemiacetal carbon with an asterisk. Indicate whether cellobiose is a reducing sugar and undergoes mutarotation. 

Cellobiose is a reducing sugar and undergoes mutarotation because it contains a hemiacetal group. 

Cellobiose, like maltose, is a reducing sugar that, on acid-catalyzed hydrolysis, yields two molar equivalents of o-glucose. Cellobiose also undergoes mutarotation and forms a monophenylosazone. Methylation studies show that C1 of one glucose unit is connected... 

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