Sorbose systems

In this investigation, three main focus areas are reported (1) S. aureus growth in homogeneous liquid media system, (2) mold spore germination in heterogeneous semi-solid starch-sugars and cellulose-sorbose systems with, and (3) survival of organisms in freeze-dried locust bean and xanthan... 

The main drawback of the system is that the ketone catalyst slowly decomposes during the reaction, which means that 0.2-0.3 equivalents are needed for complete conversion. More robust catalysts, which can be used in 1-3 mol%, have recently been reported, but have not as yet been widely applied [8]. Ketone 1 is commercially available, or can easily be synthesized in large scale in two steps from d-fructose. Ent-1 is obtained in a similar way from L-sorbose. 

The Enzymes II (E-IIs) of the phosphoenolpyruvate (P-enolpyruvate)-dependent phosphotransferase system (PTS) are carbohydrate transporters found only in prokaryotes. They not only transport hexoses and hexitols, but also pentitols and disaccharides. The PTS substrates are listed in Table I. The abbreviations used (as superscripts) throughout the text for these substrates are as follows Bgl, jS-gluco-side Cel, cellobiose Fru, fructose Glc, glucose Gut, glucitol Lac, lactose Man, mannose Mtl, mannitol Nag, iV-acetylglucosamine Scr, sucrose Sor, sorbose Xtl, xylitol. 

Fig. 17. Schematic diagram of the flow system used for batch and continuous oxidation of DAS (Diacetone-L-sorbose) with a swiss roll cell with an anode area of 3 m2...

In works made under direction of N.M. Emanuel they showed that catalytic system [Cu2+... A. .. 02] where A" - the anion form of substrate (anion form of substrate was formed at the expense of its deprotonation under the action of bases introduced into the system) is extremely effective in reactions of oxidation of fluorinated alcohols with general formula H(CF2CF2)nCH2OH (where n=l-6) [2], camphor [3] and diacetone-L-sorbose [4] with... 

In order to completely separate the physiological effect of the solute, another system was designed. A mutant strain of A. nidulans (biA-1 sorA-2) was selected because of its defect in L-sorbose transportation into the cells. In the wild strain, A. nidulans allows L-sorbose transportation. The media... 

The D-fructose transport-system seems to be highly sugar-specific, although a decrease in uptake occurs in the presence of D-sorbose, D-glucose, D-galactose, 3-O-methyl-D-glucose, and sucrose. Little effect on uptake is shown by the presence of D-arabinose, D-fucose, D-man-nose, L-sorbose, D-tagatose, and D-xylose.17... 

The best catalytic system for oxidation of sorbose in terms of activity and selectivity were platinum containing catalysts, e.g. 1TPS-Pt2. For this catalyst a long induction period was noted (Figure 6). 

Similar effects take place with the glassy solutions of carbohydrates which are also characterized by the presence of the hydrated forms. The formation of e tr has been found in the solutions of glucose, galactose, sorbose, rhamnose, maltose, and saccharose (52). For instance, in the case of 4-5M solutions of glucose the EPR spectrum of e tr is essentially a narrow line with AH 10 1 oe. in H20 and 5 = 1 oe. in D20 (see Figure 6). The parameters of the optical band of e tr in these solutions are given in Table IV. In the system under consideration G(e tr) = 1.5 ( 50% ). 

L-sorbose by acetal exchange with 2,2-dimethoxypropane, as catalyzed by p-toluenesulfonic acid. The diacetal 16, namely, l,2 3,4-di-O-isopropylidene-a-L-sorbofuranose, is, however, a most improbable intermediate, as it would have a strained, trans-iused system of five-membered rings. 

To address these issues, we studied the catalytic behavior of Pt nanoparticles formed in several nanostructured polymeric systems in the selective oxidation of L-sorbose to 2-keto-L-gulonic acid (Table 3.5) [89]. Commercial Pt/7-Al203 (3% Pt, Degussa AG) was used for comparison. The reaction has been conducted in alkaU media (NaHCOs), yet gradual alkaline loading (NaHCOs) provides the highest selectivity, while one-shot results in the highest TOP. 

Raman and i.r. spectra of crystalline D-fructose, L-sorbose, 5-deoxy-D-threo-hexulose (1.e., 5-deoxy-D-fructose), and D-arablnose In the 3100-3650, 2800-3000, and 200-1600 cm regions and the Raman spectra in the 10-200 cm region have been reported. Bands due to OH stretching were correlated with 0H.H distances and results discussed In relationship to relative sweetness. The hydrogen-bond system In crystalline a-D-glucopyranose has been... 

The aldehyde and ketone units appear in some biologically important systems. The ketone unit appears in many carbohydrates (sugars), including ribulose (85), fructose (86), and sorbose (87). d-Ribulose is an intermediate in the fungal pathway for d-arabitol production as the l,5-6is(phosphate), d-ribulose combines with carbon dioxide at the start of the photosynthetic process in green... 

Fig. 12.2 Classical two-step fermentation process. The D-glucose was hydrogenated to form D-sorbitol. The D-sorbitol was converted into L-sorbose by acetic acid bacteria. The L-sorbose was further oxidized with a mixture culture system with B. megaterium and K. vulgare to form 2-KLG. The 2-KLG was then esterified and lactonized to form vitamin C. The only difference between the classical two-step process and the Reichstein process is the replacement of low efficient protective oxidation with a fermentation process. The G. oxydans here was further identified to be K. vulgare...

Yin GL, He JM, Ren SX, Song Q, Ye Q, Lin YH, Chen CS, Guo XY (1997) Production of vitamin C precursor-2-leto-L-gulonic acid from L-sorbose by a novel bacterial component system of SCB329-SCB933. Ind Microbiol 27 1-7... 

In this section, a highly efficient synthetic system for the preparation of 2-C-hydroxymethylaldopentoses is discussed. The reactions of four different keto-hexoses (o-psicose, D-fructose, L-sorbose and D-tagatose) were studied imder various conditions in order to elucidate the relationship between the two key processes, the coordination of the sugar to the nickel complex, and the rearrangement of the carbon skeleton of the substrate ketose. The system was then compared with that of the epimerization of the aldose/nickel(II)/ethylenediamine complex. 

In this context, it appears to be of relevance to briefly mention some comparable reaction systems for ketose epimerization. Petrus and his group, as well as Petrus, Serianni and co-workers, recently reported the stereospecific molybdic acid catalyzed isomerization of 2-hexuloses to branched-chain aldoses [55-57]. Upon treatment with a catalytic amount of molybdic acid in aqueous solution, the 2-ketohexoses, o-fructose, L-sorbose and o-tagatose, underwent a stereospecific intramolecular rearrangement to give the corresponding 2-C-hydroxyme-thylaldoses, 2-C-hydroxymethyl-D-ribose (o-hamamelose), 2-C-hydroxymethyl-L-lyxose and 2-C-hydroxymethyl-o-xylose, respectively (see Petrus, Petrusova and Hricovfniova, this vol.). 

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