D-Glucose residue

Among the spectroscopic methods applicable to polysaccharides, u.v. spectrophotometry is of little value for characterizing heparin, whose main, electronic chromophore (the C02 group) displays a band at 220 nm, that is, in a region where all glycosaminoglycans absorb (also through their N-acetyl chromophores), and where minor proportions of unsaturated or aromatic contaminants cause serious interference.77 With pure heparin preparations, the carboxylate chromophore is most useful for chiroptical measurements, and a semi-quantitative evaluation of the extent of N-acetylation of 2-amino-2-deoxy-D-glucose residues is also possible.78... 

OH-3 and the ring-oxygen atom, 0-5, of the first and second D-glucose residues from the steroid residue. The hydrogen-atom positions were reported in the second publication.135... 

The polysaccharides of Type VIII pneumococcus,1 1 Friedlander s bacillus,1 2 Rhizobiam and Azotobacter evidently have closely related structures and they contain a high proportion of D-glucose residues. Cross reactions indicated that oxidized cellulose has affinities with this group.1 ... 

D-Glucose residue 1 would therefore appear as 2,3,4,6-tetramethyl-D-glucose on hydrolysis of methylated dextran D-glucose 2 as 2,3-dimethyl-D-glucose and the other three D-glucose residues as 2,3,4-tri-... 

The unit cell is tetragonal, with a = b = 10.7 A (1.07 nm) and c = 16.1 A (1.61 nm). The amylose helix is left-handed, with four D-glucose residues per turn. Both ions are located in a water-like environment. The atoms 0-2, 0-3, and 0-4 from D-glucose residues on adjacent chains coordinate around K+. The R factor is 41%. 

The unit cell is tetragonal, with a symmetry approximating P2i2 2i. The cell dimensions are a = b= 18.87 A (1.887 nm) and c = 7.99 A (799 pm). The helix diameter is 13.3 A (1.33 nm). One ethylenediamine molecule for every two D-glucose residues is indicated. The location of the ethylenediamine molecule in the lattice was discussed. The structure is almost identical to that of the amy-lose-dimethyl sulfoxide complex. 

Electron diffraction by lamellar, single crystals leads to a two-dimensional, tetragonal unit-cell with a = b = 22.9 A (2.29 nm). From X-ray diffraction data obtained from a film of sedimented, lamellar crystals, it was found that the c axis spacing (7.8 A 780 pm) is equivalent to that in 6-fold and 7-fold amylose helices. The true helical diameters of the 1-butanol, isopropyl alcohol, and 1-naphthol complexes were calculated from experimental data. The ratios of 6 7 8 indicated that the 1-naphthol complex has eight D-glucose residues per turn. The diversity of helical orientations in V-amylose crystals was discussed. 

The space group is P2i2i2 . The unit cell is pseudotetragonal, with a = b = 19.17 A (1.917 nm), and c = 24.39 A (2.439 nm), with two antiparallel chains per cell. The amylose chain is a left-handed 6(—1.355) helix, with three turns per crystallographic repeat. One molecule of dimethyl sulfoxide for every three D-glucose residues is located inside the helix. An additional 4 molecules of dimethyl sulfoxide and 8 of water are located in the interstices. The interstitial dimethyl sulfoxide is the source of additional layer-lines that are not consistent with the 8.13 A (813 pm) amylose repeat. The overall R factor is 35%, and, for the layer lines with amylose contribution alone, it is 29%. 

The molecules are helices having a twofold screw-axis, with an axial rise per disaccharide residue of 9.45 A (945 pm). The axes of the chains are parallel, and about equally spaced, but are not further organized into crystalline arrays. A hydrogen bond was proposed between the OH-3 group of the 2-acetamido-2-deoxy-D-glucose residues and 0-5 of the D-galactose 6-sulfate residues. 

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... 

This stopping or stabilization reaction with cellulose was presumed to involve a saccharinic acid rearrangement of the reducing group on the terminal D-glucose residue. This mechanism was confirmed by the formation of D-glucometasaccharinic acid, which still remained attached as the terminal unit (73). The stopping reaction is presented in Scheme 13. 

This enzyme [EC 3.2.1.3] catalyzes the hydrolytic release of/3-D-glucose from terminal 1,4-linked a-D-glucose residues successively from nonreducing ends of polysaccharide chains. 

---