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Haworth projection of the structures for α-D-glucopyranose and α-L-glucopyranose. In chemistry, a Haworth projection is a common way of writing a structural formula to represent the cyclic structure of monosaccharides with a simple three-dimensional perspective.
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.
Allulose, also known by its systematic name D-ribo-2-hexulose as well as by the name D-psicose, is a monosaccharide and a ketohexose. [ 2 ] [ 11 ] It is a C3 epimer of fructose . [ 2 ] Fructose can be converted to allulose by the enzymes D -tagatose 3-epimerase ( EC 5.1.3.31 ) and/or D -psicose 3-epimerase ( EC 5.1.3.30 ), which has allowed for ...
Haworth Projection of β-D-glucopyranose. Hermann Emil Fischer won the Nobel Prize in Chemistry (1902) for his work in determining the structure of the D-aldohexoses. [1] However, the linear, free-aldehyde structures that Fischer proposed represent a very minor percentage of the forms that hexose sugars adopt in solution.
From left to right: Haworth projections and ball-and-stick structures of the α- and β- anomers of D-glucopyranose (top row) and D-glucofuranose (bottom row) In solutions, the open-chain form of glucose (either " D -" or " L -") exists in equilibrium with several cyclic isomers , each containing a ring of carbons closed by one oxygen atom.
Mannose is a sugar with the formula HOCH 2 (CHOH) 4 CHO.It is one of the monomers of the aldohexose series of carbohydrates.It is a C-2 epimer of glucose.Mannose is important in human metabolism, especially in the glycosylation of certain proteins.
The stereochemical structure of a cyclic monosaccharide can be represented in a Haworth projection. In this diagram, the α-isomer for the pyranose form of a D -aldohexose has the −OH of the anomeric carbon below the plane of the carbon atoms, while the β-isomer has the −OH of the anomeric carbon above the plane.
The aldohexose that is most important in biochemistry is D-glucose, which is the main "fuel" for metabolism in many living organisms. The 2-ketohexoses psicose, fructose and tagatose occur naturally as the D-isomers, whereas sorbose occurs naturally as the L-isomer. D-Sorbose is commonly used in the commercial synthesis of ascorbic acid. [10]