Poly fructoses

In polyfructoses, a distinction can be made between the inulin (dahlin) group with 1,2-glycosidically linked fructose units and the phlean group with 2,6-glycosidic bonds. Polyfructoses occur as food reserve material in the roots, leaves, and seeds of various plants. In addition, they are produced by certain kinds of bacteria, e.g., laevans, which belong to the phlean group. 

The polyfructose content of grasses alters in the course of the year for example, it passes through a maximum in about the middle of May and then falls again. In contrast, the cellulose content continually increases. Since cattle, unlike man, can digest cellulose, but prefer not to eat it, and since the food value falls as the cellulose content increases, the grass is cut toward the middle of May. 

Pigman and R. M. Goegg, Jr., Chemistry of the Carbohydrates, Academic Press, New York, 1948. 

Micheel, Chemie der Zucker und Polysaccharide, Akad. Verlagsges., Leipzig, 1956. 

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The production of D-glucose-1-phosphate as an intermediate does not seem to be necessary in other polysaccharide syntheses. Cane sugar (sucrose, saccharose), for example, is converted by the action of the enzyme dextran saccharase into dextran, a poly(glucose), with fructose as by-product. Another product of saccharose is levane, a poly(fructose) produced by the action of the enzyme levane saccharase through release of glucose. 

MgS04, stability could be maintained at high temperatures up to 1 mol/dml Thus, these cloud point measurements give conclusive evidence of the unique behavior of polymeric surfactants based on inulin. The poly fructose chain remains hydrated up to high temperatures and in the presence of high electrolyte concentrations. Thus, by adequate design of the polymeric surfactant, one can achieve very high stability for the emulsions. 

The treatment of sucrose with anhydrous HF89 results in the formation of a complex mixture of pseudooligo- and poly-saccharides up to dp 14, which were detected by fast-atom-bombardment mass spectrometry (FABMS). Some of the smaller products were isolated and identified by comparison with the known compounds prepared86 88 a-D-Fru/-1,2 2,1 -p-D-Fru/j (1), either free or variously glucosylated, was a major product, and this is in accord with the known stability of the compound. The mechanism of formation of the products in the case of sucrose involves preliminary condensation of two fructose residues. The resultant dianhydride is then glucosylated by glucopyranosyl cation.89 The characterization of this type of compound was an important step because it has permitted an increased understanding of the chemical nature of caramels. 

In 1993, the di-D-fructose dianhydrides were summarized as being of little, if any, commercial importance. 73 However, a search of the literature reveals an appreciable number of patents issued since 1989 for the manufacture of these compounds. These include enzymic methods for the production of individual dianhydrides (Ref. 130) or methods of production of mixtures using anhydrous HF or pyridinium poly(hydrogen fluoride) (see Ref. 131). Most cite the di-D-fructose dianhydrides as low-calorie sweetening agents (Ref. 132), and some claim anti-cariogenic properties (Refs. 132 and 133). 

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

Other compounds identified in caramels are di-D-fructose and poly(glycosyl) dianhydrides (DFAs). DFAs were found in caramels prepared from D-fructose, D-glucose, and sucrose. The analysis was done after derivatization as TMS (per-0-trimethylsilyl) derivatives or as TMS-oxime (per-O-trimethylsilyl oxime) by... 

Fluorescent pseudomonads are capable of synthesizing poly(3HAMCL)s from a large number of substrates. Work on the biotechnological production of poly(3HAMCL) has focused mainly on two model systems - Pseudomonas oleo-vorans and P. putida. P. oleovorans is able to use alkanes and alkenes as substrate due to the presence of the OCT-plasmid while P. putida, which does not have this plasmid, cannot. In contrast to P. oleovorans, however, P. putida can use carbohydrates such as glucose and fructose for the production of poly(3HAMCL). 

When cells are grown on non-aliphatic substrates, such as glucose, fructose, acetate, or glycerol, these are converted to appropriate precursors that can be incorporated into poly(3HAMCL)s via fatty acid synthesis. The resulting PHAs have a monomer composition that is similar to that seen after growth on alkanes, often with 3-hydroxydecanoic acid as the major monomer. ( -Oxidation does not seem to play a role in the conversion of these substrates into poly(3HAMCL) since the addition of a -oxidation inhibitor did not affect the monomer composition [47]. 

Optically pure a, . (R)-3-hydroxybutanoates can be obtained by alcoholysis of poly-(R)-3-hydroxybutanoate, a fermentation product of fructose by Alcaligones eutrophus.4 (S)-Ethyl 3-hydroxybutanoate in 84-87% ee can be synthesized in 57-67% yield on a decagram-scale by an Organic Syntheses procedure6 using bakers yeast reduction of ethyl 3-oxobutanoate with the aid of sucrose.7 In order to obtain enantioselectivity as high as 95-97% ee, the substrate concentration should be kept below 1 g/L.6... 

Gibbs energy change is available to enable synthesis of oligo- and poly-saccharides by sucrose-type enzymes that use sucrose as a substrate for the transfer of glucose or fructose. 

Zenkl et al. [51] presented another approach to design saccharide-sensitive nanobeads. They prepared particles (0 380 nm) based on poly (/V- i sopropy I aery I am ide) cross-linked with phenylboronic acid moieties. In the presence of a saccharide (glucose or fructose) the particles reversibly swell due to the formation of negative charges. A FRET-indicator couple (fhiorescein/rhodamine) is used to monitor the... 

An early example of an MIP-QCM sensor was a glucose monitoring system by Malitesta et al. (1999). A glucose imprinted poly(o-phenylenediamine) polymer was electrosynthesized on the sensor surface. This QCM sensor showed selectivity for glucose over other compounds such as ascorbic acid, paracetamol, cysteine, and fructose at physiologically relevant millimolar concentrations. A unique QCM sensor for detection of yeast was reported by Dickert and coworkers (Dickert et al. 2001 Dickert and Hayden 2002). Yeast cells were imprinted in a sol-gel matrix on the surface of the transducer. The MIP-coated sensor was able to measure yeast cell concentrations in situ and in complex media. A QCM sensor coated with a thin permeable MIP film was developed for the determination of L-menthol in the liquid phase (Percival et al. 2001). The MIP-QCM sensor displayed good selectivity and good sensitivity with a detection limit of 200 ppb (Fig. 15.7). The sensor also displayed excellent enantioselectivity and was able to easily differentiate the l- and D-enantiomers of menthol. 

Synthesis from Poly-alcohols.—We come, now, to that group of mono-saccharoses, the hexose mono-saccharoses, which contains the most important simple sugars which are known, viz., glucose and fructose. The hexoses may be prepared, synthetically, by oxidizing the hexa-hydroxy alcohols, e.g. mannitol, dulcitol, sorbitol, etc. (p. 219). 

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