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Two monosaccharides with equivalent molecular graphs (same chain length and same carbonyl position) may still be distinct stereoisomers, whose molecules differ in spatial orientation. This happens only if the molecule contains a stereogenic center , specifically a carbon atom that is chiral (connected to four distinct molecular sub-structures).
Glucose is a monosaccharide containing six carbon atoms and an aldehyde group, and is therefore an aldohexose. The glucose molecule can exist in an open-chain (acyclic) as well as ring (cyclic) form. Glucose is naturally occurring and is found in its free state in fruits and other parts of plants.
In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. [1] The chemical formula of many pentoses is C 5 H 10 O 5, and their molecular weight is 150.13 g/mol. [2] Pentoses are very important in biochemistry. Ribose is a constituent of RNA, and the related molecule, deoxyribose, is a constituent of DNA.
Deoxyribose, or more precisely 2-deoxyribose, is a monosaccharide with idealized formula H−(C=O)−(CH 2)−(CHOH) 3 −H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of a hydroxy group. Discovered in 1929 by Phoebus Levene, [4] deoxyribose is most notable for its presence in DNA.
Otherwise, if the carbonyl position is 2 or 3, the sugar is a derivative of a ketone, and is called a ketohexose, a special case of ketose; specifically, an n-ketohexose. [ 1 ] [ 2 ] However, the 3-ketohexoses have not been observed in nature, and are difficult to synthesize; [ 5 ] so the term "ketohexose" usually means 2-ketohexose.
Mannose is a dominant monosaccharide in N-linked glycosylation, which is a post-translational modification of proteins. It is initiated by the en bloc transfer on Glc 3 Man 9 GlcNAc 2 to nascent glycoproteins in the endoplasmic reticulum (ER) in a co-translational manner as the protein entered through the transport system.
Carbohydrate synthesis is a sub-field of organic chemistry concerned with generating complex carbohydrate structures from simple units (monosaccharides). The generation of carbohydrate structures usually involves linking monosaccharides or oligosaccharides through glycosidic bonds, a process called glycosylation. Therefore, it is important to ...
Fischer projection of D-glyceraldehyde. Like most carbohydrates, simple aldoses have the general chemical formula C n (H 2 O) n.Because formaldehyde (n=1) and glycolaldehyde (n=2) are not generally considered to be carbohydrates, [1] the simplest possible aldose is the triose glyceraldehyde, which only contains three carbon atoms.