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Iditol
Iditol is a sugar alcohol which accumulates in galactokinase deficiency. See also *Idose *Aldose reductase *L-iditol 2-dehydrogenase External links * Sugar alcohols {{biochemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar Alcohol
Sugar alcohols (also called polyhydric alcohols, polyalcohols, alditols or glycitols) are organic compounds, typically derived from sugars, containing one hydroxyl group (–OH) attached to each carbon atom. They are white, water-soluble solids that can occur naturally or be produced industrially by hydrogenation of sugars. Since they contain multiple –OH groups, they are classified as polyols. Sugar alcohols are used widely in the food industry as thickeners and sweeteners. In commercial foodstuffs, sugar alcohols are commonly used in place of table sugar (sucrose), often in combination with high-intensity artificial sweeteners, in order to offset their low sweetness. Xylitol and sorbitol are popular sugar alcohols in commercial foods. Chemical structure Sugar alcohols have the general formula HOCH2(CHOH)''n''CH2OH. In contrast, sugars have two fewer hydrogen atoms, for example HOCH2(CHOH)''n''CHO or HOCH2(CHOH)''n''−1C(O)CH2OH. The sugar alcohols differ in chain length. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactokinase Deficiency
Galactokinase deficiency is an autosomal recessive metabolic disorder marked by an accumulation of galactose and galactitol secondary to the decreased conversion of galactose to galactose-1-phosphate by galactokinase. The disorder is caused by mutations in the GALK1 gene, located on chromosome 17q24. Galactokinase catalyzes the first step of galactose phosphorylation in the Leloir pathway of intermediate metabolism. Galactokinase deficiency is one of the three inborn errors of metabolism that lead to hypergalactosemia. The disorder is inherited as an autosomal recessive trait. Unlike classic galactosemia, which is caused by deficiency of galactose-1-phosphate uridyltransferase, galactokinase deficiency does not present with severe manifestations in early infancy. Its major clinical symptom is the development of cataracts during the first weeks or months of life, as a result of the accumulation, in the lens, of galactitol, a product of an alternative route of galactose utilizatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Idose
Idose is a hexose, a six carbon monosaccharide. It has an aldehyde group and is an aldose. It is not found in nature, but its uronic acid, iduronic acid, is important. It is a component of dermatan sulfate and heparan sulfate, which are glycosaminoglycans. The first and third hydroxyls point the opposite way from the second and fourth. It is made by aldol condensation of D- and L-glyceraldehyde. L-Idose is a C-5 epimer of D-glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using .... References Aldohexoses {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldose Reductase
In enzymology, aldose reductase (or aldehyde reductase) () is a cytosolic NADPH-dependent oxidoreductase that catalyzes the reduction of a variety of aldehydes and carbonyls, including monosaccharides. It is primarily known for catalyzing the reduction of glucose to sorbitol, the first step in polyol pathway of glucose metabolism. Reactions Aldose reductase catalyzes the NADPH-dependent conversion of glucose to sorbitol, the first step in polyol pathway of glucose metabolism. The second and last step in the pathway is catalyzed by sorbitol dehydrogenase, which catalyzes the NAD-linked oxidation of sorbitol to fructose. Thus, the polyol pathway results in conversion of glucose to fructose with stoichiometric utilization of NADPH and production of NADH. ;glucose + NADPH + H+ \rightleftharpoons sorbitol + NADP+ Galactose is also a substrate for the polyol pathway, but the corresponding keto sugar is not produced because sorbitol dehydrogenase is incapable of oxidizing galactitol. Ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L-iditol 2-dehydrogenase
In enzymology, a L-iditol 2-dehydrogenase () is an enzyme that catalyzes the chemical reaction :L-iditol + NAD+ L-sorbose + NADH + H+ Thus, the two substrates of this enzyme are L-iditol and NAD+, whereas its 3 products are L-sorbose, NADH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-iditol:NAD+ 2-oxidoreductase. Other names in common use include polyol dehydrogenase, sorbitol dehydrogenase, L-iditol:NAD+ 5-oxidoreductase, L-iditol (sorbitol) dehydrogenase, glucitol dehydrogenase, L-iditol:NAD+ oxidoreductase, NAD+-dependent sorbitol dehydrogenase, NAD+-dependent sorbitol dehydrogenase, and NAD+-sorbitol dehydrogenase. This enzyme participates in fructose and mannose metabolism Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, es ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
