Of a -D-glucose

Example Hrady investigated classical dyriam ics of a-d-glucose in... 

Example Brady investigated classical dynamics of a-d-glucose in water.In this simulation, 207 water molecules surrounded one a-d-glucose. The system was in a cubic box with periodic boundary conditions. During the simulation, several hydroxyl group transitions occurred. These transitions are normally unlikely with an in vacuo simulation. 

You can detect hydroxyl group transitions by plotting dihedral angles versus time over the course of the simulation. This is the distance history. Brady investigated the distance history of water 19. Brady, J.W. Molecular dynamics simulations of a-d-glucose in aqueous solution. 

Aminoglycoside Biosynthesis. The biosynthesis of the aminoglycosides has been extensively studied and reviewed (117—119). Perhaps the most interesting aspect is the biosynthesis of 2-deoxystreptamiae (1, R = H), in which the C-1 and C-6 of a D-glucose molecule become the C-1 and C-2 of 2-deoxystreptamiae by way of the intermediate 2-deoxy-j //(9-iaosose. The details of this conversion are stiU unclear. 

The conformational symbols for enantiomers are different. It is therefore important to state in the context whether the d or the L form is under consideration. Enantiomers have the same reference plane (see 2-Caib-7.3), and it should be noted that the mirror image of a-D-glucose-4Ci is a-L-glucose-C4. 

Glycogen is the major storage carbohydrate in animals, corresponding to starch in plants it is a branched polymer of a-D-glucose. It occurs mainly in liver (up to 6%) and muscle, where it rarely exceeds 1%. However, because of its greater mass, muscle contains about three to four times as much glycogen as does liver (Table 18—1). 

The pronounced proclivity of phosphoric monoester monoanions to eliminate POf is not always recognizable from the characteristic pH profile of Fig. 1. The hydrolysis rate maximum at pH w 4 may be masked by a faster reaction of the neutral phosphoric ester, as in the case of a-D-glucose 1-phosphate63) or on hydrolysis of monobenzyl phosphate 64). In the latter case, the known ability of benzyl esters to undergo SN1 and SN2 reactions permits fast hydrolysis of the neutral ester with C/O bond breakage. The fact that the monoanion 107 of the monobenzyl ester is hydrolyzed some 40 times faster than the monoanion 108 of the dibenzyl ester at the same pH again evidences the special hydrolysis pathway of 107, rationalized by means of the metaphosphate hypothesis. 

The regioselective esterification at position 6 of a-D-glucose and a-D-glucopyrano-sides with fatty acids [81] is readily achieved by use of Novozym 435, in accordance with Scheme 8.56. 

Leloir110(a) has described a conversion of D-mannosyl phosphate to D-mannose 6-phosphate by phosphoglucomutase, and here, too, the reaction requires catalytic quantities of a-D-glucose 1,6-diphosphate. The role of the latter is probably to generate a-D-mannose 1,6-diphosphate as follows. 

Fractionation of mycobacteria resulted in the identification of two cellular immunostimulatory components, namely TDM and MDPs. Both are normally found in association with the mycobacterial cell wall. TDM is composed of a molecule of trehalose (a disaccharide consisting of two molecules of a-D-glucose linked via an a 1-1 glycosidic bond), linked to two molecules of my-colic acid (a long-chain aliphatic hydrocarbon-based acid) found almost exclusively in association with mycobacteria. TDM, although retaining its adjuvanticity, is relatively non-toxic. 

As bacterial transglucosidase is instrumental in the transfer of a D-glucose residue from one acceptor to another, so does yeast hexokinase 3 catalyze a transphosphorylation. The highly specific donator of a labile phosphate group is adenosine triphosphate (XX), the fermentable hexoses D-glucose, D-mannose and D-fructose functioning as acceptors. Hexokinase catalyzes the reaction... 

Irradiation of a-D-glucose 6-(disodium phosphate)188 (100) yields products that retain the phosphate group (see Table XXIV) but are otherwise the same as those formed from irradiation of D-glucose itself (see Table XII). Photolysis of a-D-glucosyl (dipotassium phosphate)... 

These water-soluble molecules are cyclic oligomers of a-D-glucose formed by the action of certain bacterial amylases on starches (Bender and Komiyama, 1978 Saenger, 1980 Szejtli, 1982). a-Cyclodextrin (cyclohexa-amylose) has six glucose units joined a(l, 4) in a torus [1], whereas /3-cyclodextrin (cycloheptaamylose) and y-cyclodextrin (cyclooctaamylose) have seven and eight units, respectively. 

The oxidation of a-D-glucose occurs at less than 1% of the rate of oxidation of the /3 anomer. Because these two forms exist in solution in equilibrium in the proportion of 36% (a) and 64% (/3), mutarotation of the a to the /3 form must be allowed to reach equilibrium in the sample and standards for consistent... 

A solution of a-D-Glucose in water obeys Henry s law up to high concentrations and throughout a wide range of temperature and pressure. (Note This does not mean that the Henry s law constant k is independent of pressure... 

We reported a catalytic enantioselective cyanosUylation of ketones that produces chiral tetrasubstituted carbons from a wide range of substrate ketones [Eq. (13.31)]. The catalyst is a titanium complex of a D-glucose-derived ligand 47. It was proposed that the reaction proceeds through a dual activation of substrate ketone by the titanium and TMSCN by the phosphine oxide (51), thus producing (l )-ketone cyanohydrins ... 

Certain procedures make it possible to obtain the a and 3 anomers of glucose in pure form. A 1-molar solution of a-D-glucose has a rotation value [a]o of +112°, while a corresponding solution of p-D-glucose has a value of +19°. These values change spontaneously, however, and after a certain time reach the same end point of +52°. The reason for this is that, in solution, mutarotation leads to an equilibrium between the a and p forms in which, independently of the starting conditions, 62% of the molecules are present in the P form and 38% in the a form. 

Oxidation of the carboxyl-reduced and acetylated Pneumococcus type 2 capsular polysaccharide revealed that only one L-rhamnose residue in the hexasaccharide repeating-unit, later demonstrated to have the structure 60, was oxidized and, consequently, /3-L-linked.156 Replacement of 2,3,6-tri-O-methyl-D-glucose in the methylation analysis of the original polysaccharide by 2,3,4,6-tetra-O-methyl-D-glucose in that of the oxidized polysaccharide established that this L-rhamnose residue is linked to 0-4 of a D-glucose residue. The analysis also showed that it was an L-rhamnose residue in the chain (and not the branching L-rhamnose residue) that was /3-linked. 

A freshly prepared solution of a-D-glucose shows a specific rotation of +112°. Over time, the rotation of the solution gradually decreases and reaches an equilibrium value corresponding to [ci ]d5°c = +52.5°. In contrast, a freshly pre-... 

Glycogen is synthesized from molecules of a-D-glucose. The process occurs in the cytosol, and requires energy supplied by ATP (for the phosphorylation of glucose) and uridine triphosphate (UTP). 

For the biosynthesis of inositols and of the benzene rings of aromatic a-amino acids nature employs nucleophilic centers at C-6 of a D-glucose-derived hexos-5-ulose phosphate [5] and at C-7 of a 3,7-dideoxyhept-2,6-diulosonic acid [6], respectively, ions 1 and 2... 

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