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However, these compounds are not known to occur in nature, and are difficult to synthesize. [5] In 1897, an unfermentable product obtained by treatment of fructose with bases, in particular lead(II) hydroxide, was given the name glutose, a portmanteau of glucose and fructose, and was claimed to be a 3-ketohexose.
Glucose isomerase (also known as xylose isomerase) catalyzes the conversion of D-xylose and D-glucose to D-xylulose and D-fructose. Like most sugar isomerases, glucose isomerase catalyzes the interconversion of aldoses and ketoses. [24] The conversion of glucose to fructose is a key component of high-fructose corn syrup production.
Oligosaccharides of glucose combined with other sugars serve as important energy stores. These include lactose, the predominant sugar in milk, which is a glucose-galactose disaccharide, and sucrose, another disaccharide which is composed of glucose and fructose. Glucose is also added onto certain proteins and lipids in a process called ...
For example, there are 16 distinct aldohexose stereoisomers, but the name "glucose" means a specific pair of mirror-image aldohexoses. In the Fischer projection, one of the two glucose isomers has the hydroxyl at left on C3, and at right on C4 and C5; while the other isomer has the reversed pattern.
It is now known that isomerases have broad substrate specificity. Most pentoses and some hexoses are all substrates for D-xylose isomerase. Some examples include D-ribose, L-arabinose, L-rhamnose, and D-allose. [7] Conversion of glucose to fructose by xylose isomerase was first patented in the 1960s.
Note that, in this nomenclature, mirror-image isomers differ only in the ' D '/' L ' prefix, even though all their hydroxyls are reversed. The following tables shows the Fischer projections of selected monosaccharides (in open-chain form), with their conventional names. The table shows all aldoses with 3 to 6 carbon atoms, and a few ketoses.
Fructose can be bad for your health when consumed as part of high-fructose corn syrup in processed foods. Past studies have linked high-fructose corn syrup intake to many diseases, including cancer.
Fructose (/ ˈ f r ʌ k t oʊ s,-oʊ z /), or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose.It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed by the gut directly into the blood of the portal vein during digestion.