Enzymes D-glucose

That the same enzyme,28 sucrose phosphorylase, is involved in the reaction of L-arabinose is indicated by the following observation. When L-arabinose is added to a mixture containing the enzyme, D-glucose-1-phosphate and D-fructose, of which the last is present in insufficient concentration to give the maximum rate of sucrose formation, an increase... 

D-Glucose-l-phosphate + enzyme => D-glucose-enzyme + phosphate. 

Arsenate, which can apparently serve as glucose acceptor to the enzyme-D-glucose complex but which does not form a stable glucose ester, causes the rapid decomposition of both sucrose and D-glucose-l-phosphate in accordance with the following equations 44... 

One of them involves the enzymes D-glucose-l-oxidase (EC 1.1.3.4) and pyranose-2-oxidase (EC 1.1.3.10). An alternative enzymatic pathway (Scheme 9, Path b) requires the same two enzymes, but proceeds through the intermediate o-arabino-hexos-2-ulose, D-glucosone, (107) the enzyme catalase can be used to decompose the H202.283... 

Enzyme D-Glucose oxidase (free or glutaraldehyde-cross-linked) E.C. No. U.3.4... 

A stable enzyme-D-glucose intermediate has been obtained in the hydrolysis of methyl a-D-[ C]glucopyranoside by an a-D-glucosidase from Saccharomyces oviformis Phenol was used to terminate the reaction and to trap the intermediate in a rapid-flow technique. The intermediate appears to be covalently linked, since continuous washing of the denatured protein failed to remove the radiolabel, which was also retained by a tryptic peptide isolated by gel filtration. Treatment of the intermediate with acid released D-[ C]glucose. The radiolabel was not bound when the enzyme was replaced with bovine albumin or when jS-D-glucosylamine (a potent inhibitor of a-D-glucosidase) was added with the enzyme. 

To avoid interference with the active site of the enzyme, D-glucose oxidase from Aspergillus niger has been immobilized by way of its carbohydrate moieties. Thus, treatment of the periodate-oxidized enzyme with a styrene derivative afforded a water-insoluble material retaining full enzymic activity and exhibiting enhanced thermal stability at 60 °C. 

D-glucose, dextrose, C Hi20 . The most common hexose sugar. It is present in many plants, and is the sugar of the blood. It is a constituent of starch, cellulose, glycogen, sucrose and many glycosides, from all of which it can be obtained by hydrolysis with acids or enzymes. 

One of the most exciting discoveries related to quinone/hydroquinone chemistry is thek synthesis by biosynthetic routes (12,13). Using bacterial enzymes to convert D-glucose [50-99-7] (7) to either 1,2- or l,4-ben2enediol allows the use of renewable raw material to replace traditional petrochemicals. The promise of reduced dependence on caustic solutions and the use of transition-metal catalysts for thek synthesis are attractive in spite of the scientific and economic problems still to be solved. 

P-amylase, and debranching enzymes. Conversion of D-glucose to D-fmctose is mediated by glucose isomerase, mosdy in its immobilized form in columns. Enzymic degradation of starch to symps has been well reviewed (116—118), and enzymic isomerization, especially by immobilized glucose isomerase, has been fiiUy described (119) (see Syrups). 

Enzymes are specific, however. For example, starch is depolymerized using enzymes to D-glucose (dextrose). The solution of glucose is then treated with glucose isomerase [9055-00-9] to give D-fmctose in about 42% yield. No D-mannose is formed. Addition of isolated D-fmctose to this solution gives the common 55% high fmctose com symp (HFCS) so widely used in soft drinks in the United States. HFCS is about 1.5 times as sweet as sucrose. 

D-Glucose is produced by complete depolymerization of starch with enzymes that catalyze the hydrolysis of both its (1 — 4) and (1 — 6) linkages. Crystalline a-D-glucopyranose is generally sold as dextrose. Glucose is also isomerized to D-fmctose to produce high fmctose com symp (HFCS). 

Oligo- and higher saccharides are produced extensively by acid-and/or enzyme-catalyzed hydrolysis of starch, generally in the form of symps of mixtures (12). These products are classified by thek dextrose equivalency (DE), which is an indication of thek molecular size and is a measure of thek reducing power with the DE value of anhydrous D-glucose defined as 100. 

Liver contains an enzyme called glucokinase, which also carries out the reaction in Figure 19.4 but is highly specific for D-glucose, has a much higher for glucose (approximately 10.0 mAf), and is not product-inhibited. With such... 

Glycogen synthase also exists in two distinct forms which can be interconverted by the action of specific enzymes active, dephosphorylated glycogen synthase I (glucose-6-P-independent) and less active phosphorylated glycogen synthase D (glucose-6-P-dependent). The nature of phosphorylation is more complex with glycogen synthase. As many as nine serine residues on the enzyme appear to be subject to phosphorylation, each site s phosphorylation having some effect on enzyme activity. 

Immunopolysaccharides. Part VIII. Enzymic Synthesis of 6-0-a-D-Glucopyranosyl-3-0-methyl-D-glucose by Betacoccus arabinosaceous," S. A. Barker, E. J. Boume, P. M. Grant, and M. Stacey, /. Chem. Soc., (1958) 601-604. 

Hager M, Currie F, Holmberg K (2003) Organic Reactions in Microemulsions. 227 53-74 Hausler H, Stiitz AE (2001) d-Xylose (d-Glucose) Isomerase and Related Enzymes in Carbohydrate Synthesis. 215 77-114... 

S] + K )] for the hexokinase-catalyzed phosphorylation reactions of 2DG and D-glucose, respectively [S (substrate) + E (enzyme) — ES— -I- P (product)]. This constant (LC) accounts for the ratio of the arteriovenous extraction fraction (by transport and phosphorylation) of 2DG to that of D-glucose (LC= 1) under steady-state conditions. This concept can be directly applied to the case of 2DFG by employing the LC (-0.5) for 2DFG. 

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