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The name glucose is derived from ... 198.17 g/mol, [49] [50] that for anhydrous D-glucose is 180.16 g ... rise to four distinct cyclic isomers: α-D ...
l-Glucose is an organic compound with formula C 6 H 12 O 6 or O=CH[CH(OH)] 5 H, specifically one of the aldohexose monosaccharides. As the l-isomer of glucose, it is the enantiomer of the more common d-glucose. l-Glucose does not occur naturally in living organisms, but can be synthesized in the laboratory.
These prefixes are attached to the systematic name of the molecular graph. So for example, D-glucose is D-gluco-hexose, D-ribose is D-ribo-pentose, and D-psicose is D-ribo-hexulose. Note that, in this nomenclature, mirror-image isomers differ only in the ' D '/' L ' prefix, even though all their hydroxyls are reversed.
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.
Each pair has a conventional name (like "glucose" or "fructose"), and the two members are labeled "D-" or "L-", depending on whether the hydroxyl in position 5, in the Fischer projection of the molecule, is to the right or to the left of the axis, respectively. These labels are independent of the optical activity of the isomers.
As an example, D-glucose is an aldohexose and has the formula C 6 H 12 O 6. Four of its six carbon atoms are stereogenic, which means D -glucose is one of 2 4 =16 possible stereoisomers. [ 20 ] [ 21 ]
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.
For example, regardless of the configuration of the starting D-glucose, a solution will gradually move towards being a mixture of approximately 64% β-D-glucopyranoside and 36% of α-D-glucopyranose. As the ratio changes, the optical rotation of the mixture changes; this phenomenon is called mutarotation .