Sugars isomerization

Some biomass-derived contaminants, on the other hand, may affect the catalytic processing rate. Ammonium shows significant inhibition calcium may also have an effect. Potassium, though, appears to have too little interaction to be noticeable at the concentrations tested. The common acid anions phosphate, sulfate, and chloride appear to have no effect, while nitrate changes the conversion route and the product slate through a sugar isomerization mechanism. These tests show that while some contaminants may affect the catalytic processing rate, most have no impact, and there is no indication of a combinatorial effect on the catalyst when several of the contaminants are present in the feedstock. Consequently, the calcium and ammonium continue to be the key components of concern. 

In the electrolyzed fluid from mannite Renard obtained formic acid, trio xymethylene, oxalic acid, a sugar isomeric with glucose, and an. acid, CeHgOg, which he regarded as the aldehyde of saccharic acid. He could not detect mannonic acid-Erythrite is oxidized to a great extent. 

There are about twenty naturally occurring amino acids in all each, when pure, is a whitish powder with a faint but distinctive smell. The formulae of some of the more important of them are listed in Table 4. As with the sugars, isomeric forms of the amino acids can exist, as mirror-images of one another, thus ... 

Sugars Isomerization of glucose, hydrolysis of starch, hydrolysis of cellulose, hydrolysis of sucrose Rehm and Reed (1984)... 

Dijkmans J, Gabriels D, Dusselier M, de Clippel F, Vanelderen P, Houthoofd K, et al. Productive sugar isomerization with highly active Sn in dealuminated [small beta] zeolites. Green Chem 2013 15 2777-85. 

Coenzymes of isomerases and lyases Uridine diphosphate UDP Sugar isomerization XVII-4... 

Lactose on hydrolysis gives glucose and an isomeric monosaccharide galactose, which may be given the symbol Ga-r. The lactose molecule may be represented as Ga-r-G-r, and it has therefore also a free potential aldehyde group and is a reducing sugar like maltose. 

Among sucrose glucose and fructose fructose is the sweetest Honey is sweeter than table sugar because It contains fructose formed by the isomerization of glucose as shown in the equation... 

Fructose—Dextrose Separation. Emctose—dextrose separation is an example of the appHcation of adsorption to nonhydrocarbon systems. An aqueous solution of the isomeric monosaccharide sugars, C H 2Dg, fmctose and dextrose (glucose), accompanied by minor quantities of polysaccharides, is produced commercially under the designation of "high" fmctose com symp by the enzymatic conversion of cornstarch. Because fmctose has about double the sweetness index of dextrose, the separation of fmctose from this mixture and the recycling of dextrose for further enzymatic conversion to fmctose is of commercial interest (see Sugar Sweeteners). 

Liquid sucrose and Hquid invert, generally made by redissolving white sugar and inverting with invertase enzyme, are refinery products in Europe and outside the United States. In the United States they have been almost completely replaced by cheaper com symps made by enzymatic hydrolysis of starch and isomerization of glucose. 

The primary steps in the conversion of starch are Uquefaction, saccharification, and isomerization. By controlling the enzymatic reactions, sugars of different sweetness can be produced to suit the various needs of manufacturers of food and nonalcohoUc beverages. 

Glucose Isomeriza.tion, Enzymatic isomerization of glucose to fmctose provides a real alternative to sugar (sucrose) derived from sugarcane or sugarbeets. The commercial product obtained is known as high fmctose com symp (HECS). Two grades of the symp have become estabUshed on the world market, HECS-42 and HECS-55, which contain 42 and 55% fmctose on dry substance basis. These products account for over one-third of the caloric sweetener market ia the United States. 

All known eight-stranded a/p-barrel domains have enzymatic functions that include isomerization of small sugar molecules, oxidation by flavin coenzymes, phosphate transfer, and degradation of sugar polymers. In some of these enzymes the barrel domain comprises the whole subunit of the protein in others the polypeptide chain is longer and forms several additional domains. An enzymatic function in these multidomain subunits, however, is always associated with the barrel domain. 

In the second method, which can be applied to compounds with an optically active center near the potentially tautomeric portion of the molecule, the effect of the isomerization on the optical activity is measured. In favorable cases both the rate of racemization and the equilibrium position can be determined. This method has been used extensively to study the isomerization of sugars and their derivatives (cf. reference 75). It has not been used much to study heteroaromatic compounds, although the very fact that certain compounds have been obtained optically active determines their tautomeric form. For example, oxazol-5-ones have thus been shown to exist in the CH form (see Volume 2, Section II,D,1, of article IV by Katritzky and Lagowski). 

An isomeric sugar, D-javose, is a constituent of two cardenolide glycosides (strophanthojavoside and antiarojavoside) found (42) in the seeds of Antiaris toxicaria Lesch. Degradative studies indicated (42) that javose had the structure 6-deoxy-2-0-methyl-D-allose (17) and this assignment was confirmed by two stereospecific syntheses. 

Attempts to separate the isomeric deoxy ribose phosphates by ion exchange techniques met with no success this may be because of the fact that eluents having a pH lower than 5 were not used, as migration of phosphomonoesters is known to be acid catalysed, and, because of the free sugar involved, alkaline eluents could not be considered. 

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