A- Glucose

Conversion of (3- into a-glucose penta-acetate. Add 0-5 g. of anhydrous zinc chloride rapidly to 25 ml. of acetic anhydride in a 200 ml. round-bottomed flask, attach a reflux condenser, and heat on a boiling water bath for 5-10 minutes to dissolve the solid. Then add 5 g. of the pure P glucose penta-acetate, and heat on a water bath for 30 minutes. Pour the hot solution into 250 ml. of ice water, and stir vigorously in order to induce crystaUisation of the oily drops. Filter the solid at the pump, wash with cold water, and recrystaUise from methylated spirit or from methyl alcohol. Pure a-glucose penta-acetate, m.p. 110-111°, will be obtained. Confirm its identity by a mixed m.p. determination. 

Immobilization. The fixing property of PEIs has previously been discussed. Another appHcation of this property is enzyme immobilization (419). Enzymes can be bound by reactive compounds, eg, isothiocyanate (420) to the PEI skeleton, or immobilized on soHd supports, eg, cotton by adhesion with the aid of PEIs. In every case, fixing considerably simplifies the performance of enzyme-catalyzed reactions, thus faciHtating preparative work. This technique has been appHed to glutaraldehyde-sensitive enzymes (421), a-glucose transferase (422), and pectin lyase, pectin esterase, and endopolygalacturonase (423). 

There appears to be a chromium pool in individuals who are not chromium deficient (136). When there is an increase in level of cHculating insulin in response to a glucose load, an increase in circulating chromium occurs over a period of 0.5—2 h. This is foUowed by a decline and excretion of chromium in urine increases. Chromium deficiency is indicated when no increase or a small increase in blood chromium level or urine chromium occurs. 

Cochineal Extract. Cochineal extract (Cl Natural Red 4, Cl No. 75470 EEC No. E 120) is the concentrated solution obtained after removing the alcohol from an aqueous-alcohoHc extract of cochineal, which is the dried bodies of the female insect Coccus cacti Dactylopius coccus costd) a variety of field louse. The coloring principle of the extract is beHeved to be carminic acid [1260-17-9] (40), an hydroxyanthraquinone linked to a glucose unit, comprising approximately 10% of cochineal and 2—4% of its extract. 

FeCl3, AC2O, 55-75% yield.The relative rates of cleavage for the 6-, 3-, and 2-O-benzyl groups of a glucose derivative are 125 24 1. Sulfuric acid has also been used as a catalyst. ... 

Bu3SnOMe, CICH2CH2CI, 1 h, 77% yield.These conditions selectively cleave the anomeric acetate of a glucose derivative in the presence of other acetates. 

Analysis of pure cellulose indicates an empirical formula CgHigOj corresponding to a glucose anhydride. There is ample evidence to indicate that in fact cellulose is a high molecular weight polyanhydroglucose. In particular it may be... 

Cellulase The enzyme that cuts the linear chain of cellulose, a glucose polymer at 1-4-p-linkages into cellodextrins and glucose. 

Mix a few drops of a glucose solution with a few drops of an alcoholic solution of n-naphthol and poui slowly down the side of the test-tube a few drops of cone, sulphunc acid. A violet colouration is produced. (Molisch s reaction.) See AppendiXt p. 271. 

Write a balanced equation for the synthesis of a glucose molecule from ribulose-l,5-bisphosphate and COg that involves the first three reactions of the Calvin cycle and subsequent conversion of the two glyceraldehyde-3-P molecules into glucose. 

Cells require a constant supply of N/ X)PH for reductive reactions vital to biosynthetic purposes. Much of this requirement is met by a glucose-based metabolic sequence variously called the pentose phosphate pathway, the hexose monophosphate shunt, or the phosphogluconate pathway. In addition to providing N/VDPH for biosynthetic processes, this pathway produces ribos 5-phosphate, which is essential for nucleic acid synthesis. Several metabolites of the pentose phosphate pathway can also be shuttled into glycolysis. 

D-Glucose can be crystallized in two different forms, a-glucose and p-glucose . The forms have different melting points, and different specific rotations when dissolved in water. These rotations change upon standing to give a solution whose specific rotation is +52.7°. 

Glykosid. n. glycoside, glucoside. (Preferably, glycoside is the general term, glucoside denotes a glucose derivative.)... 

Recently, two examples of the separation of enantiomers using CCC have been published (Fig. 1-2). The complete enantiomeric separation of commercial d,l-kynurenine (2) with bovine serum albumin (BSA) as a chiral selector in an aqueous-aqueous polymer phase system was achieved within 3.5 h [128]. Moreover, the chiral resolution of 100 mg of an estrogen receptor partial agonist (7-DMO, 3) was performed using a sulfated (3-cyclodextrin [129, 130], while previous attempts with unsubstituted cyclodextrin were not successful [124]. The same authors described the partial resolution of a glucose-6-phosphatase inhibitor (4) with a Whelk-0 derivative as chiral selector (5) [129]. 

The citric acid cycle, a nine-step process, also diverts chemical energy to the production of ATP and the reduction of NAD and FAD. In each step of the citric acid cycle (also known as the Krebs cycle) a glucose metabolite is oxidized while one of the carrier molecules, NAD or FAD, is reduced. Enzymes, nature s chemical catalysts, do a remarkable job of coupling the oxidation and reduction reactions so that energy is transferred with great efficiency. 

When crystals of pure a-glucose are dissolved in water, isomerization slowly occurs to produce /3-glucose. Propose a mechanism for the isomerization. 

Refer to Problem 55 and determine the concentration of a glucose solution isotonic with blood. 

Disaccharides, which are dimers farmed when two monosaccharide units combine with the elimination of H20. The monosaccharides may be the same (two glucose units in maltose) or different (a glucose and fructose unit in sucrose). 

Sucrose, the compound we call sugar, is the most common disaccharide. One of the monomer units in sucrose is a-glucose. The other is fructose, a monosaccharide found in honey and natural fruit juices. 

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