Monosaccharides crystal structure

Table 7.11. O-H -O Hydrogen-bond lengths from neutron diffraction of carbohydrates, and from combined (normalized) X-ray and neutron diffraction data from 43 monosaccharide crystal structures...

These rules permitted the known monosaccharide crystal structures to be classified into four different hydrogen-bonding schemes. On the basis of these three rules, it was found that the 44 crystal structures for which neutron or good X-ray data were available at the time of the analysis, could be divided into four classes, which are shown in Thble 13.2. 

The Water Molecules Link Hydrogen-Bond Chains into Nets in the Hydrated Monosaccharide Crystal Structures... 

Eijck B P, W T M Mooij and J Kroon 1995. Attempted Prediction of the Crystal Structures of Six Monosaccharides. Acta Crystallographica B51 99-103. 

With monosaccharides, the structures of the relatively rigid pyranoses and methylpyranosides in the crystalline state can be accurately pr icted if the hydroxyl groups are oriented as in the crystal, in the directions appropriate to form... 

In monosaccharides where structures differ at C-1 and C-2, hut are the same in the rest of the molecule, we get the same phenylosazone. If we examine the structures of glucose and mannose, the only structural difference we can identify is the orientation of the hydroxyl group at C-2. The rest of the molecules are exactly the same. Therefore, glucose and mannose produce the same phenylosazone. Phenylosazones are highly crystalline solids with characteristic shaped crystals. Shapes are diagnostic of phenylosazone type. 

The more stable boron chelates can be isolated even from aqueous solution, whereas those of lower stabilities are only accessible from non-aqueous media. Catechol- and inositol-borates (3, 5 and 6) possesses a well-defined monomeric structure,75 whereas those obtained from monosaccharides and alditols are polymeric.121 A crystal structure determination122 has been carried out for sodium scyUo-inositol diborate (6). 

Zhang, B., S. Zhang, and K. Wang. 1996. Synthesis, characterization and crystal structure of cyclic vanadate complexes with monosaccharide derivatives having a free adjacent diol system. J. Chem. Soc., Dalton Tram. 3257-3263. 

Ideally, any study of hydrogen-bond geometries should be based solely on single crystal neutron diffraction studies. It is only for the amino acids [60], and the monosaccharides [58, 59] that any attempt has been made to systematically study a significant number of crystal structures of closely related biological molecules by neutron diffraction. For the peptides, disaccharides, and the nucleic acid components, no systematic neutron diffraction studies have been made, and data are available only for a few isolated examples. 

In di- and trisaccharide crystal structures and in cyclodextrins, intramolecular hydrogen bonds have been observed between adjacent monosaccharides, as shown by the representative examples given in Thble 9.3 and shown in Fig. 9.1. If these... 

For the carbohydrates especially, the amount of available crystal structural data decreases sharply with molecular complexity [479]. With the exception of the cyclodextrins, discussed in Part III, Chapter 18, there are less than 40 crystal structure analyses of oligosaccharides, of which less than 10 are trisaccharides, one is a tetrasaccharide, and one a hexasaccharide (Part III, Chap. 18). The majority of the basic monosaccharides that are the subunits of the polysaccharides that occur naturally have been studied for example, the pyranose forms of /7-arabinose, a-xylose, a- and -glucose, / fructose, a-sorbose, a-mannose, a- and -galactose, a-fucose, a-rhamnose, N-acetyl glucosamine, and mannosamine (Box 13.2). How-... 

The crystal structure of the biologically active, heparin-decasaccharide-linked dimer of aFGF exhibits a unique mode of ligand-induced protein dimerization. This aFGF dimer is bridged by heparin and does not have a pro-tein-proteininterface. Instead, the protomers are positioned to bind sulphate groups of five to six monosaccharide units on opposite sides of the heparin helix axis. 

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