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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. Haworth projection approximate the shapes of the actual molecules better for furanoses —which are in reality nearly planar—than for pyranoses that exist in ...
The Fischer projection is a systematic way of drawing the skeletal formula of an acyclic monosaccharide so that the handedness of each chiral carbon is well specified. Each stereoisomer of a simple open-chain monosaccharide can be identified by the positions (right or left) in the Fischer diagram of the chiral hydroxyls (the hydroxyls attached ...
Sir Walter Norman Haworth FRS [1] (19 March 1883 [2] – 19 March 1950) was a British chemist best known for his groundbreaking work on ascorbic acid while working at the University of Birmingham. He received the 1937 Nobel Prize in Chemistry "for his investigations on carbohydrates and vitamin C".
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 ...
2, 3 = Haworth projections. 4 = Mills projection. Every two anomers are designated alpha (α) or beta (β), according to the configurational relationship between the anomeric centre and the anomeric reference atom , hence they are relative stereodescriptors . [ 2 ]
The given definition is the one used by IUPAC, which recommends the Haworth projection to correctly assign stereochemical configurations. [ 4 ] Many authors require in addition that the sugar be bonded to a non-sugar for the molecule to qualify as a glycoside, thus excluding polysaccharides .
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However, the linear, free-aldehyde structures that Fischer proposed represent a very minor percentage of the forms that hexose sugars adopt in solution. It was Edmund Hirst and Clifford Purves, in the research group of Walter Haworth , who conclusively determined that the hexose sugars preferentially form a pyranose, or six-membered, ring.