Chemistry
D Fructose
D-fructose is a simple sugar, also known as a monosaccharide, that is commonly found in fruits, honey, and root vegetables. It is a key component of many biomolecules and plays a crucial role in energy metabolism. Structurally, it is a ketohexose, meaning it has six carbon atoms and contains a ketone functional group.
Written by Perlego with AI-assistance
Related key terms
1 of 5
7 Key excerpts on "D Fructose"
eBook - PDF- H. Stephen Stoker(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
From the third to the sixth carbon, the structure of D -fructose is identical to that of D -glucose. Differences at carbons 1 and 2 are related to the presence of a ketone group in fructose and of an aldehyde group in glucose. CHO A A A A A A O O OO O O CH 2 OH OH H A A OO OH OH H HO H H D -Glucose A A A A A A OO O O CH 2 OH CH 2 OH HO OH H H A A O O OH H C P O D -Fructose Same structure d-Ribose D -Glucose, D -galactose, and D -fructose are all hexoses. D -Ribose is a pentose. If car-bon 3 and its accompanying ! H and ! OH groups were eliminated from the struc-ture of D -glucose, the remaining structure would be that of D -ribose. CHO A A A A O O OO O O CH 2 OH OH H A A A A OO OH OH H HO H H D -Glucose CHO A A A A A A A A O O O O CH 2 OH OH OO OH OH H H H D -Ribose D -Ribose is a component of a variety of complex molecules, including ribo-nucleic acids (RNAs) and energy-rich compounds such as adenosine triphosphate (ATP). The compound 2-deoxy-D -ribose is also important in nucleic acid chemistry. This monosaccharide is a component of DNA molecules. The prefix deoxy - means “minus an oxygen”; the structures of ribose and 2-deoxyribose differ in that the latter compound lacks an oxygen atom at carbon 2. CHO A A A A A O O O O CH 2 OH OH A A A OO OH OH H H H D -Ribose CHO A A A A A A O O O O CH 2 OH H OO OH OH H H H C 2-Deoxy-D -ribose Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 266 CHAPTER 7 Carbohydrates 7-10 Cyclic Forms of Monosaccharides L E A R N I N G F O C U S Be able to use Haworth projection formulas to denote the cyclic forms of monosaccharides.
eBook - PDFGeneral, Organic, and Biological Chemistry
An Integrated Approach
- Kenneth W. Raymond(Author)
- 2012(Publication Date)
- Wiley(Publisher)
10.3 Important Monosaccharides and Monosaccharide Derivatives 381 PRACTICE PROBLEM 10.4 Figure 10.9 shows two of the eight possible d-aldohexoses. Draw the other six. 10.3 I M P O R TA N T M O N O S A C C H A R I D E S A N D M O N O S A C C H A R I D E D E R I VAT I V E S While monosaccharides of various sizes appear in nature, pentoses and hexoses are the most abundant. d-Ribose and d-2-deoxyribose are aldopentoses that are often incorpo- rated into larger biomolecules, including the biochemical reducing agent NADPH, the biochemical oxidizing agent NAD + , and the nucleic acids RNA and DNA (Chapter 13). D-Ribose H¬ H¬ H¬ O ‘ C ƒ ¬ ƒ ¬ ƒ ¬ ƒ C ¬H ¬OH ¬OH ¬OH H 2 OH D-2-Deoxyribose H¬ H¬ H¬ O ‘ C ƒ ¬ ƒ ¬ ƒ ¬ ƒ C ¬H ¬H ¬OH ¬OH H 2 OH The structural difference between these two monosaccharides is that 2-deoxyribose lacks an i OH group on carbon atom 2, hence the “2-deoxy” part of the name. This is just one example of the variations in monosaccharide structure that are observed in nature. d-Glucose (Figure 10.9), also known as dextrose or blood sugar, is one of the most impor- tant monosaccharides in human biochemistry. It is released when the polysaccharides starch and glycogen are broken down and is a key reactant in the series of reactions that produces compounds used to drive otherwise nonspontaneous biochemical reactions. One form of energy storage in the body involves combining glucose molecules to produce glycogen. d-Galactose (Figure 10.9) is combined with glucose to produce lactose (Section 10.5), an oligosaccharide that gives milk its sweetness. When lactose is digested, the galactose released is transformed into a glucose derivative used for energy production or storage. Galactose and glucose are diastereomers, and one of the key steps in the conversion of galactose into a glucose derivative involves flipping the orientation of the chiral carbon atom at position 4.
eBook - PDFDietary Sugars
Chemistry, Analysis, Function and Effects
- Victor R Preedy(Author)
- 2012(Publication Date)
- Royal Society of Chemistry(Publisher)
This molecular group can be defined as polyhydroxy aldehydes and polyhydroxy ketones or as substances that can release these compounds when they are hydrolysed. Their general chemical formula is [C(H 2 O)] n , where n Z 3. However, even though the majority of the saccharides present this empirical formula, some carbohydrates can include nitrogen, phosphorus or sulphur in their structures. The simplest carbohydrates, which cannot be hydrolysed into smaller sub-units, are known as monosaccharides. Monosaccharides can be one unit polyhydroxy aldehydes or polyhydroxy ketones. D-glucose is the most Food and Nutritional Components in Focus No. 3 Dietary Sugars: Chemistry, Analysis, Function and Effects Edited by Victor R Preedy r The Royal Society of Chemistry 2012 Published by the Royal Society of Chemistry, www.rsc.org 86 abundant of the monosaccharides and has a fundamental role in the energetic metabolism of living organisms. Another important monosaccharide is D-galactose. This sugar contains six carbons (hexose) and is frequently observed associated with glucose in the disaccharide lactose (Figure 6.1), which is present in the milk of mammals. D-galactose, like D-glucose, is an energetic source in cell metabolism. Information on galactose metabolism will be discussed in other chapters of this book. Briefly, in this biochemical process, D-galactose is converted into galactose-6-phosphate by the action of the enzyme galactokinase (GALK) through the consumption of ATP. After this reaction, UDP-galactose is obtained through the action of the enzyme galactose-1-phosphate uridyl-transferase (GALT). The enzyme UDP-galactose 4-epimerase catalyses the regeneration of UDP-glucose in the final step of normal galactose metabolism (Holden et al . 2003). After these reactions, glucose-6-phosphate is obtained through the action of a transferase and the enzyme phosphoglucomutase. Glucose-6-phosphate is then able to enter into the glycolysis pathway.
eBook - PDF- P Karlson(Author)
- 1975(Publication Date)
- Academic Press(Publisher)
Free mannose occurs in plants, but more often is bound. In the animal organism, it is a component of glycolipids (Chapter XIII,4), glycoproteins, and blood group substances. D-( + y Galactose is a component of milk sugar (lactose) and other oligosaccharides and of a few other more complicated compounds. It differs from glucose in the steric configuration at C-4; as a consequence, three hydroxyls in the ring form are eis. An enzyme is able to convert galactose to glucose, i.e., it performs a Waiden inversion at C-4 (glucose 4-epimerase ; coenzyme : uridine diphosphate). Nitric acid oxidation of galactose produces mucic acid (tetrahydroxyadipic acid) in its meso form. This reaction was important in the determination of its constitution. Besides the common D -isomer, L -galactose also occurs naturally (in agar agar and elsewhere). H O -C -H H -C -O H I H O -C -H I H -C -O H I H-C CH 2 OH ß -D -Glucose CH 2 OH C =0 I H O -C -H H -C -O H I H -C -O H I CH 2 OH HO-C-CH 2 OH H O -C -H H -C -O H C-I CH 2 OH D -Fructose, projection formulas CH 2 OH ß-D -Glucose H 7 > 0 O H CH 2 OH /?-D -Fructofuranose D'(—)-Fructose 9 a ketohexose, was at one time called lévulose, because it rotates polarized light to the left. Nevertheless, it belongs to the D -series and is closely related to D -glucose (see formulas above). Free fructose largely exists in the pyranose form 3 0 0 X V . S I M P L E S U G A R S , M O N O S A C C H A R I D E S (six-membered ring); only in oligosaccharides (cane sugar), in polysaccharides (inulin), and in several phosphate esters is the furanose form realized. Fructose occurs mainly in the plant kingdom and in honey. Two phosphate esters, fructose 6-phosphate (Neuberg ester) anD Fructose 1,6-bisphosphate (Harden-Young ester) are biochemically significant because they are intermediates in the breakdown of glucose according to the Embden-Meyerhof pathway (Section 7) ; this pathway is actually the route of breakdown of fructose 1,6-bisphosphate.
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
706 CHAPTER 27 • Carbohydrates compromise in portraying the three-dimensional configuration of such molecules. Structural models are much more effective, especially if constructed by the student. The two cyclic forms of D-glucose differ only in the relative positions of the i H and i OH groups attached to carbon 1. Yet this seemingly minor structural difference has important bio- chemical consequences because the physical shape of a molecule often determines its biological use. For example, the fundamental structural difference between starch and cellulose is that starch is a polymer of a-D-glucopyranose, whereas cellulose is a polymer of b-D-glucopyranose. As a consequence, starch is easily digested by humans, but we are totally unable to digest cellulose. Galactose, like glucose, is an aldohexose and differs structurally from glucose only in the configuration of the i H and i OH group on carbon 4. Galactose is an epimer of glucose and vice versa. H O C CH 2 OH OH H H HO H HO OH H 1 2 3 4 5 6 D-galactose differs from D-glucose here H O C CH 2 OH OH H H HO OH H OH H 1 2 3 4 5 6 D-glucose Galactose, like glucose, also exists primarily in two cyclic pyranose forms that have hemiacetal structures and undergo mutarotation: CH 2 OH OH OH O 5 6 4 1 3 2 5 CH 2 OH OH OH O 6 4 1 3 2 �-D-galactopyranose �-D-galactopyranose OH OH OH OH � � Fructose is a ketohexose. The open-chain form may be represented in a Fischer projection formula: CH 2 OH CH 2 OH H HO OH H OH H 1 2 3 4 5 6 D-fructose This portion has the same configuration as D-glucose. O C keto group H H H O O H H H H O O O H H H H H O (a) Ball-and-stick model (b) Spacefilling model Figure 27.4 Three-dimensional representations of the chair form of a-D-glucopyranose. To identify anomers in the Haworth formula, focus on carbon 1 for aldoses and carbon 2 for ketoses.
eBook - PDFPenta- and Higher Polyhydric Alcohols, Their Oxidation Products and Derivatives, Saccharides
A Modern Comprehensive Treatise
- S. Coffey(Author)
- 2013(Publication Date)
- Elsevier(Publisher)
(a) Nomenclature, structure and stereochemistry (i) Early history It is appropriate to discuss the structural representation of the mono-saccharides by following its historical development. Elemental analysis of glucose by Dumas in 1843 showed it to have the empirical formula CH 2 0, hence the origin of the term carbohydrate (French, hydrate de carbone; German, Kohlenhydrate). It was not until the i92o's that the complete structure of glucose was unravelled and the molecule now represents one of the most thoroughly investigated of organic structures. The knowledge gained has been extended to its many relatives and consequently carbohydrate chemistry is an extension or outgrowth of scientific study of the structure and chemical properties of glucose. The trivial names given to the simple monosaccharides by the earlier workers now form the basis of the systematic nomenclature recommended by British and American chemists (for references see p. 7). Molecular weight determinations established the molecular formula of glucose as C 6 H 12 0 6 (B. Tollens and H. Mayer, Ber., 1888, 21, 1566). The presence of only five esterifiable hydroxyls was revealed by the isolation of a crystalline penta-0-acetate (A. P. N. Franchimont, ibid., 1879, I2 > τ 93&)· The aldehydic character of glucose was shown by its oxidation to a hexonic acid (gluconic acid) and by its reduction to a hexitol (glucitol) without loss of carbon atoms. Furthermore, H. Kiliani {ibid., 1886, 19, 767) found that glucose forms a cyanohydrin, hydrolysis of which gave a heptonic acid containing one more carbon atom than the sugar from which it was derived. He exploited this reaction by reducing the heptonic acid with hydriodic acid i NOMENCLATURE; STRUCTURAL REPRESENTATION 69 and phosphorus to w-heptanoic acid, a most important observation since it revealed that the six carbon atoms of glucose are in the form of a straight chain with a terminal aldehyde group.
eBook - PDFCarbohydrate Chemistry
Volume 26
- R J Ferrier(Author)
- 2007(Publication Date)
- Royal Society of Chemistry(Publisher)
2: Free Sugars 11 bonds in aqueous sucrose as evaluated from i.r. data,51 and on the thermodynamics of viscous flow of sucrose soIutions.52 The effect of temperature on the concentration of the open-chain form of D-fructose in D20 and water has been determined by FT-IR spectro~copy?~ Measurements by 'H-n.m.r. spectroscopy of the temperature coefficients of chemical shifts, scalar coupling constants, and exchange rates for hydroxyl protons in sucrose have provided no evidence for persistent hydrogen bonds in aqueous solution. 4 Isomerization The C-2 epimerization of aldoses promoted by C o o N,N,N'-trimethylethylenediamine complexes has been shown, by use of i3C-labekd substrates, to involve a skeletal rearrangement. 0-11- 13c]ghcose, for example, gave D-[2-'3C]m~ose.55 D-Fructose was isomerizedto hamamelose [2-c- (hydroxymethy1)-D-ribose] by N i O N,N'-diethylethylene-diamine. The equilibrium mixture contained 29% of the branched component.'6 CHlOH x b O H - X G CH2OH OH 47 X = OBn, F, or N, OH 48 Reagents: i, immobilized glucose isomerase Scheme 11 Glucose isomerase has been employed to convert D-gluco- and L-ido-furanose derivatives 47 into D-fructo- and L-sorbo-pyranose derivatives 48, respectively, in 70 - 80% yield, as shown in Scheme 1 1.57 P-D-hCtOfuranOSe has been found to bind to DNA preferentially, allegedly by three hydrogen bonds to phosphate. DNA thus moves the equilibrium P-D-fructofuranose r. a -~ -hctofuranose to the right5' 5 Oxidation The role of the crystalline surface structure, and in particular long range surface order, of platinum electrodes in the electrwxidation of D-glucose in acidic media has been discus~ed.~*~ Papers have been published on the effects of adsorbed anions on the oxidation of D-glucose on gold single crystal electrodes,6' and on the oxidation of D-sorbose and 2,3:4,6-di-O-isopropylidene-a-L-sorbose by air over supported platinum and palladium catalysts.62
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
