Glucosidic linkage

The configuration of the glucoside linkage is different in the two, however. Structures [I] and [II], respectively, illustrate that the linkage is a /3-acetal-hydrolyzable to an equitorial hydroxide—in cellulose, and an a-acetal-hydrolyz-able to an axial hydroxide—in amylose, a starch ... 

Cellulose may be degraded by a number of environments. For example, acid-catalysed hydrolytic degradation will eventually lead to glucose by rupture of the l,4-(3-glucosidic linkages. Intermediate products may also be obtained for which the general term hydrocellulose has been given. 

Enzymic and Chemical Synthesis of the a-l 2-glucosidic Linkage Enzymic Synthesis, S. A. Barker, E. J. Bourne, P. M. Grant, andM. Stacey, Nature, 178(1956) 1221-1223. 

Yeast Insoluble Polysaccharide. The structure of an insoluble polysaccharide from the yeast Saccharomyces cerevisiae was investigated by Zechmeister and Toth,90a and also by Hassid, Joslyn and McCready.904 The isolation904 of 2,4,6-trimethyl-D-glucose as the sole product of the hydrolysis of the methylated polysaccharide indicated a chain of gluco-pyranose units joined by 1,3-glucosidic linkages. 

Peterlin168 has shown that the viscometric data for potato amylose acetate in chloroform solution can be readily interpreted in terms of a random-coil model for the molecule, in which there is hindered rotation at the oxygen atom of the glucosidic linkage. 

Amylo-1 —> 6-glucosidase obtained by Cori and Larner218 from rabbit muscles, and R-enzyme isolated by Hobson, Whelan and Peat219 from potatoes and broad beans, are typical debranching enzymes, which will hydrolyze the 6 — 1-a-D-glucosidic linkage rather than the normal 4 —> 1-a-D linkage. These enzymes will therefore be particularly important in determinations of the fine structure of amylopectin, if they can be sufficiently well purified. 

The reducing values of the reaction mixtures considered here were determined by iodometric titration63 and, therefore, measure directly the number of glucosidic linkages that had been broken. The results given in Table III show that, although the number of glucosidic bonds... 

The data given in Table V show not only that pancreatic amylase hydrolyzes unfractionated starch and a linear substrate at different rates but also that, for equivalent time intervals with the same concentration of pancreatic amylase, the relative concentrations of the products formed from these two substrates differ. In addition, Table VIM,M summarizes comparative data for the products of the hydrolyses of potato starch, of com amylose, and of waxy maize starch when equivalent numbers of glucosidic linkages of these substrates had been broken. 

Using a similar reaction sequence P-(l—>4)-glucosidic linkages were very effectively installed on the support using 4-O-TBS-protected glucosyl phosphate donor 59. Thus, repetitive glycosylation and deprotection furnished trisaccharide 62 in 53% overall yield from 54 after cleavage from the resin (Scheme 6.11). 

Alpha-amylases (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) have conventionally been employed in starch liquefaction. Alpha-amylases hydrolyze the alpha-1,4-glucosidic linkages of the starch, producing maltodextrins. The alpha-amylases... 

CGTase Activity Assay. Aaivity was measured by the Pharmacia Phadebas Amylase Assay at pH 6.0, 60 C in O.IM sodium acetate (100 ppm Ca+ " ) for 15 minutes using B, stearothermophilus alpha-amylase as a standard. Alpha-amylase preparations were assayed under the same conditions. One Phadebas unit is defined as the amount of enzyme that will catalyze the hydrolysis of 1.0 micromole of glucosidic linkages of Lintner starch per minute at 6OOC, pH 6.0. 

Also referred to as endo-l,4-j8-glucanase and carboxy-methyl cellulase, this enzyme [EC 3.2.1.4] catalyzes the endohydrolysis of l,4-j8-D-glucosidic linkages in cellulose. The enzyme also catalyzes the hydrolysis of 1,4-Unkages in /3-D-glucans also containing 1,3-Unkages. 

This enzyme [EC 3.2.1.11], also known as o -l,6-glucan-6-glucanohydrolase, catalyzes the endohydrolysis of 1,6-ce-D-glucosidic linkages in dextran. 

This enzyme [EC 3.2.1.98] removes successive maltohex-aose residues from the nonreducing chain ends of 1,4-a-D-glucosidic linkages in amylaceous polysaccharides. 

This enzyme [EC 3.2.1.10] (also referred to as oUgo-1,6-glucosidase, sucrase-isomaltase, and limit dextrinase) catalyzes the hydrolysis of l,6-o -D-glucosidic linkages in isomaltose and dextrin products generated from starch and glycogen via a-amylase. See also Sucrase... 

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