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d-Ribulose is the diastereomer of d-xylulose. Ribulose sugars are composed in the pentose phosphate pathway from arabinose. [1] They are important in the formation of many bioactive substances. For example, d-ribulose is an intermediate in the fungal pathway for d-arabitol production. Also, as the 1,5-bisphosphate, d-ribulose combines with ...
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 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.
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 drew the ring as a flat hexagon with groups above and below the plane of the ring – the Haworth projection. [ 3 ] A further refinement to the conformation of pyranose rings came when Sponsler and Dore (1926) realized that Sachse's mathematical treatment of six-membered rings could be applied to their X-ray structure of cellulose . [ 3 ]
It forms ribulose 5-phosphate from 6-phosphogluconate: 6-phospho-D-gluconate + NAD(P) + ⇌ {\displaystyle \rightleftharpoons } D-Ribulose 5-phosphate + CO2 + NAD(P)H + H + It is an oxidative carboxylase that catalyses the oxidative decarboxylation of 6-phosphogluconate into ribulose 5-phosphate in the presence of NADP .
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Ribulose-5 phosphate can also be acted upon by phosphopentose epimerase to form xylulose 5-phosphate, which is used in the nonoxidative phase of the pentose phosphate pathway in humans to generate precursor molecules for the synthesis of aromatic amino acids and production of energy.