Monosaccharide constitution

D-Fmctose [57-48-7] (levulose, fmit sugar) is a monosaccharide constituting one-half of the sucrose molecule. It was first isolated from hydroly2ed cane sugar (iavert sugar) ia the late nineteenth century (1,2). Fmctose constitutes 4—8 wt % (dry sugar basis (dsb)) of many fmits, where it primarily occurs with glucose (dextrose) and sucrose (see Carbohydrates Sweeteners). It also makes up 50 wt % (dsb) of honey (3,4). 

PER (Taraldsvik and Myklestad, to be published). Thus monosaccharides constitute 36% of the total in this case where measurements were made in the exponential phase of growth. 

The simple sugars or monosaccharides are polyhydroxy aldehydes or ketones, and belong to Solubility Group II. They are termed tetroses, pentoses, hexoses. etc. according to the number of carbon atoms in the long chain constituting the molecule, and aldoses or ketoses if they are aldehydes or ketones. Most of the monosaccharides that occur in nature are pentoses and hexoses. 

Lactose is a disacchande constituting 2-6% of milk and is known as milk sugar It differs from maltose and cellobiose m that only one of its monosaccharide units is D glucose The other monosaccharide unit the one that contributes its anomeric carbon to the glycoside bond is d galactose Like cellobiose lactose is a (3 glycoside... 

Glycosyl esters with remote functionality constitute a relatively new class of O-carbonyl glycosyl donors, which fulfill the prospect of mild and chemoselective activation protocols (Scheme 3.22). For example, Kobayashi and coworkers have developed a 2-pyridine carboxylate glycosyl donor 134 (Y = 2-pyridyl), which is activated by the coordination of metal Lewis acid (El+) to the Lewis basic pyridine nitrogen atom and ester carbonyl oxygen atom [324]. In the event, 2-pyridyl (carbonyl) donor 134 and the monosaccharide acceptor were treated with copper(II) triflate (2.2 equiv) in diethyl ether at —50 °C, providing the disaccharide 136 in 70% (a P,... 

Constitutional studies have broadly followed the pattern of methyla-tion of the unsubstituted alcoholic groups in a carbohydrate, hydrolytic or oxidative disruption of the molecule and identification of the resulting methylated fragments. In this way methyl ethers have been invaluable in the determination of the ring structures of the monosaccharides and in the elucidation of the constitutions of the more complex saccharides. 

In this article, the authors have endeavored to summarize the methods of synthesis and the proofs of constitution of all the known methyl ethers of D-glucopyranose and D-glucofuranose. Acyclic glucose ethers are not considered in this review. Later articles will deal with monosaccharides other than glucose. It has not been possible to discuss in full all the reactions involved, but to offset this disadvantage the bibliography has been made as complete as possible and tables have been compiled of the physical properties of the methyl-D-glucoses and of their more important derivatives. 

The introduction of g.l.c. for oligosaccharide analysis constituted a major breakthrough in the field. In addition to strategies for accurate and sensitive quantitation of monosaccharide type (19,20), chiral procedures may be adopted for enantiomeric (d and l) determination (21). The sensitivity of h.p.a.e. chromatography with pulsed amperometric detection now provides an alternative to g.l.c. for oligosaccharide compositional analysis (22). 

The next chapter, by Ren Csuk and Brigitte I. Glanzer (Zdrich), constitutes an extensive treatise on the nuclear magnetic resonance (n.m.r.) spectroscopy of fluorinated monosaccharides [whose early chemistry was surveyed in Vol. 38 (1981) by Anna A. E. Penglis] the comprehensive data tabulated herein should be especially of value to those working in the fleld. It continues the coverage, in Advances, of n.m.r. spectroscopy as the key tool for characterization of carbohydrates. It complements articles on the H-n.m.r. spectroscopy of carbohydrates by Laurance D. Hall [Vols. 19 (1964) and 29 (1974)], Bruce Coxon [Vol. 27 (1972)], and Johannes F. G. Vliegenthart, Lambertus Dorland, and Herman van Halbeek [Vol. 41 (1983)], and on the C-n.m.r. spectroscopy of monosaccharides by Klaus Bock and Christian Pedersen [Vol. 41... 

Identification of constitutive monosaccharides two-dimensional homonuclear NMR techniques such as DQF-COSY and TOCSY are used to assign chemical-shift values for all C-bonded protons in each individual monosaccharide (96). One-dimensional NMR spectra provide useful information about the chemical shifts and scalar couplings of such well-resolved signals as methyl groups for 6-deoxy monosaccharides (fucose, quinovose, and rhamnose) at 6 1.1-1.3 ppm. 

Figure 3.24. Monosaccharides that commonly constitute the carbohydrate portion of glycoproteins. Refer to text for details. Note that individual hydrogen atoms attached to the core ring structure are omitted for clarity of presentation...

Two nucleic acids, deoxyribonucleic acid (8.1, DNA) and ribonucleic acid (8.2, RNA), constitute, respectively, the molecules that store hereditary information and those that transcribe and translate such hereditary information, thus enabling the directed synthesis of varied but specific proteins throughout the cell and the entire organism. These nucleic acids are biopolymers, composed of monomeric building units called nucleotides (figure 8.2). Just as proteins can be hydrolyzed to amino acids and polysaccharides can be hydrolyzed to monosaccharides, nucleic acids can be hydrolyzed to nucleotides. 

The analysis of monosaccharide mixtures as the permethylated derivatives was proposed early in the application of gas-liquid chromatography to carbohydrates, but the method has now been superseded by more convenient procedures.230,231 There are, however, situations in which this method is useful, such as during a structural study of a polysaccharide by the methylation technique. The mixture of partially methylated monosaccharides obtained by methanolysis may then be fully methylated, and the proportions of the various monosaccharides determined. This approach has been used, for example, in studies on a galactomannan392 and on tamarind-kernel polysaccharide.393 Such an analysis also constitutes a useful check to ensure that no significant change in the composition of the polysaccharide occurred during methylation. 

Wohl4 was the first to refer to the formation of higher saccharides by the action of acids on monosaccharides as reversion. This process, the acid-catalyzed formation of glycosidic bonds between sugar residues, constitutes the most rudimentary form of condensation polymerization. Reversion of oligosaccharides has also been observed. 0 The relationships between the hydrolysis of polysaccharides and the reversion of mono- and oligo-saccha-rides is illustrated for amylose in Fig. 1. 

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