Xanthanes, synthesis

The synthesis of xanthan has been studied in some detail and is depicted in Figure 7.10. 

There is a second large gene duster, about 35kb, also involved in the synthesis of xanthan. The predse function is unknown but it is thought to encode for proteins involved in the synthesis of sugar nucleotide diphosphates. 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

Finally, details of the synthesis of heteropolysaccharides in plants are as yet completely unknown. The structural similarities among some plant gums and such bacterial exopolysaccharides as xanthan gum suggest that similar mechanisms may be operative in bacteria and in plants. Lipid intermediates could be suggested as potential glycosyl donors in the formation of plant gums and mucilages. 

Xanthane hydride X-ray structures, 6, 903 Xanthene, 3,6-bis(dimethylamino)-synthesis, 3, 767 Xanthene, 4-cyano-synthesis, 3, 768 Xanthene, 3,6-dialkylamino-application, 3, 879 Xanthene, 2,7-dibromo-dipole moments, 3, 627 Xanthene, 3,4-dihydro-synthesis, 3, 768... 

Fig. (3). Immunization of a rabbit for synthesis of polyclonal antibodies and agar diffusion of sera from rabbits immunized with different antigens (xanthan and erythropoietin).

The optimum pH for synthesis of exopolysaccharides is normally between 6.0 and 75. For xanthan the optimum is pH 7.0 and below pH 5.0 synttiesis is severely depressed. 

Amination can be achieved by reductive amination of carboxyl groups using sodium cyano-borohydride [124]. By this method, 2-amino-2-deoxy functionalized amylose and cellulose have been produced. Reductive amination can also be applied to the synthesis of other amino derivatives of various oxidized polysaccharides such us xanthan [125] or alginic acid and galactomannans [126]. 

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