Monosaccharides

James Due north. BeMiller , in Saccharide Chemistry for Nutrient Scientists (Third Edition), 2019

Structures and classification

Carbohydrate (a term derived from the German language kohlenhydrate and the similar French hydrate de carbone) expresses the fact that almost unproblematic carbohydrates have the general elemental composition Cx(HiiO)y (that is, they are molecules that comprise carbon atoms plus hydrogen and oxygen atoms in the same ratio as they occur in water). Their composition is related to the fact that they are produced by photosynthesis from carbon dioxide and water every bit indicated by the following unbalanced equation:

CO2  +   HiiO   →   a carbohydrate   +   Oii

However, the great majority of natural saccharide compounds found in living organisms do non take the elementary empirical formula Cx(HiiO)y. Rather virtually naturally occurring carbohydrates are oligomers (oligosaccharides [Chapter 3]) or polymers (polysaccharides [Chapter iv]) made by joining sugars with the simple empirical formula or sugars with modified structures related to the simple empirical formula. While lower–molecular weight carbohydrates for food use are frequently obtained by depolymerization of natural polymers, this book begins with a presentation of the elementary sugars and builds from there to larger and more than circuitous structures.

A characteristic of carbohydrates (which are as well called saccharides) is that they contain chiral carbon atoms. A chiral carbon cantlet is a carbon atom that can exist in two unlike spatial arrangements (configurations). Chiral carbon atoms can be recognized easily because they are carbon atoms that take each of their 4 tetrahedral bonds connected to different atoms or groups of atoms. The two different arrangements of the four groups in space (configurations) are what are called nonsuperimposable mirror images (Fig. 1.i). In other words, one is the reflection of the other that ane would see in a mirror, with everything on the right in one configuration on the left in the other and vice versa (Box 1.2).

Figure 1.1. Chiral carbon atom. (A), (B), (D), and (East) represent different atoms or functional groups ii attached to carbon atom (C). Wedges signal chemic bonds projecting outward from the airplane of the page; dashes signal chemical bonds projecting into or below the plane of the page.

Box i.ii

Mirror Images

Nonsuperimposable mirror images can be illustrated by pressing the palms of your two hands together in front of yous (fingers upward). One is the reflection of the other that you would see in a mirror with everything that is on the right in ane on the left in the other and vice versa, that is, your thumbs and each of your four fingers oppose each other. Now if you orient your hands in the same direction, for case, with the palms facing away from y'all, you will see that the thumbs are on opposite sides and that your two hands are dissimilar, that is, they are chiral and nonsuperimposable mirror images. You would soon find this out if you tried to put a glove for the left mitt on the right hand, for example.

Monosaccharides are carbohydrate molecules that cannot be broken downwards by hydrolysis 2 into simpler (smaller) carbohydrate molecules. Hence, monosaccharides are at times referred to equally "simple sugars" or but :sugars," which infers that they are the simplest (smallest) of the carbohydrates. (The term saccharide is derived from saccharose, which is an old term for cane sugar. Now, it refers to any saccharide, especially a monosaccharide; but as subsequent capacity on oligo- and polysaccharides indicate, it can be practical to whatsoever size sugar. Mono is derived from the Greek word for one. In chemistry, it often ways containing merely ane, then the term monosaccharide means one saccharide or one sugar, indicating that it is a molecule equanimous of just 1 sugar unit of measurement and not of two or more sugar units joined together). Monosaccharides are the monomeric units of oligosaccharides (Chapter 3) and polysaccharides (Chapter iv), both of which contain more than one sugar (sugar) unit and can exist hydrolyzed to release their elective monosaccharides. The mutual monosaccharides used as building blocks for oligo- and polysaccharides plant in foods contain a group termed as the saccharose group.

The saccharose group, where R is a hydrogen atom (-H) (Aldoses) or a –CH2OH group (Ketoses).

Discussion of specific carbohydrate structures begins with d-glucose, the well-nigh common, nigh widely distributed, and most arable carbohydrate (if all its combined forms are considered). d-Glucose (known commercially as dextrose) is a monosaccharide. d-Glucose is both a polyalcohol (polyhydroxy compound) and an aldehyde. It and all sugars containing an aldehydic group are classified as aldoses (Table i.1). The prefix ald- indicates that they are aldehydes; the suffix -ose usually (simply not always equally you volition find out) signifies a nonpolymeric carbohydrate (that is, a monosaccharide). d-Glucose contains half-dozen carbon atoms, making it a hexose (Table 1.i); more specifically, it is an aldohexose. When the structure of d-glucose is written in a vertical straight-chain style (termed an acyclic or open-chain structure) with the aldehydic group (position 1 [C1]) at the peak and the carbon atom with the chief hydroxyl grouping attached to it at the bottom (at position vi [that is, on C6]), information technology tin can exist seen that all secondary hydroxyl groups are on carbon atoms C2, C3, C4, and C5. To brand the determination/assignment of which side of the carbon chain the hydroxyl groups are on, a convention for orientation of the carbon concatenation is used. In this convention, the carbon concatenation is oriented so that each vertical (carbon-to-carbon) bond projects into the airplane of the page and each horizontal bail projects outward from the plane of the page as in Fig. ane.ane (although in solution at that place is rotation about the vertical bonds that allows a hydroxyl group to be in any position with respect to the one above [or beneath] it, so that the molecules can really assume a large number of unlike conformations [shapes]). Each of the four carbon atoms that have a secondary hydroxyl grouping attached to it (C2, C3, C4, C5) are chiral carbon atoms because each has four unlike substituents attached to it. Each chiral center has a mirror image (Fig. 1.1), and mirror image chiral carbon atoms are not superimposable on each other, just as a person'southward two hands are mirror images and are not superimposable.

Table 1.i. Classification of monosaccharides

Number of carbon atoms Kind of carbonyl group
Aldehyde Ketone
3 triose triulose
4 tetrose tetrulose
5 pentose pentulose
6 hexose hexulose
seven heptose heptulose
8 octose octulose
ix nonose nonulose

Because each chiral carbon atom has a mirror image, at that place are 2n (where northward is the number of chiral carbon atoms) possible arrangements of these atoms. Thus, in a half dozen-carbon aldose (of which d-glucose is i), in which there are 4 chiral carbon atoms, at that place are iifour or 16 different arrangements of the carbon atoms containing 4 secondary hydroxyl groups (theoretically allowing formation of 16 different half-dozen-carbon sugars with an aldehydic grouping). Viii of these sugars belong to what is known as the D series; eight are their mirror images and belong to the L serial. (All 16 of these aldohexoses accept the empirical formula C6H12Ohalf dozen.) All sugars that have the hydroxyl group on the highest-numbered chiral carbon cantlet (C5 in the instance of d-glucose) positioned on the right-hand side (using this projection and convention for the chain conformation) are termed D sugars, and all with the highest-numbered chiral atom having its hydroxyl group on the left are classified as L sugars. (Annotation that l-glucose is the complete molecular mirror image of d-glucose and non the substance with the contrary configuration of just C5. If only the configuration of C5 is changed, the product is 50-idose [run across below].) The structure of d-glucose is shown in its open-chain (acyclic) form (chosen the Fischer project) with the carbon atoms numbered in the conventional style. As is customary, the horizontal lines indicating the covalent chemic bonds to the hydrogen atoms and hydroxyl groups are omitted in the structure on the right. Because the lowermost carbon atom (C6 in the case of d-glucose) is not chiral, the relative positions of the atoms and groups attached to it need non be designated, and it is written every bit –CH2OH. The dandy majority of carbohydrates found in foods are composed generally of aldohexoses. Shown below is the aldopentose arabinose in both the D and L forms, both of which occur in nature. Glucose is found but in the course of d-glucose.

An organic pharmacist say that d-glucose and all other carbohydrate molecules as highly functionalized because there is a functional group iii on each carbon atom. The complete functionalization of the backbone carbon cantlet construction with hydroxyl groups, a carbonyl oxygen atom (in the case of the simple sugars), and a loftier percentage of chiral carbon atoms are distinguishing features of carbohydrates.

d-Glucose, as its O6 phosphate ester 4 (d-glucose 6-phosphate), is the first sugar of photosynthesis. d-Glucose 6-phosphate (Affiliate two) is present in only small amounts considering it is apace converted into sucrose (Chapter iii) for transport to various parts of the establish where it is used for synthesis of other substances. Because d-glucose is the monomeric building unit of cellulose (Chapter 8), it can be considered to be the most abundantly available organic chemical compound on World (if its combined forms are considered). d-Glucose vi-phosphate is besides used every bit an energy source in the plant's metabolism.

There are two aldoses containing three carbon atoms: d-glyceraldehyde and l-glyceraldehyde (d- and fifty-glycerose according to formal sugar nomenclature, although these names are seldom used). Each possesses just one chiral carbon atom. Aldoses with iv carbon atoms (the tetroses) have two chiral carbon atoms. Aldoses with v carbon atoms (the pentoses) take three chiral carbon atoms and comprise the second most mutual group of aldoses. Extending the series above six carbon atoms gives heptoses, octoses, and nonoses (seven, eight, and nine carbon atoms, respectively). Nine carbon atoms is the size limit of naturally occurring sugars. Just pentoses and hexoses are institute in the mutual carbohydrates of food products. Development of the viii d-hexoses from d-glyceraldehyde is shown below using the Rosanoff autograph projection (Fig. 1.2). In the Rosanoff project, a circle represents the aldehydic grouping; horizontal lines betoken the location of each hydroxyl group on its chiral carbon atom, and the lesser of the vertical lines indicates the terminal, nonchiral hydroxymethyl (-CH2OH) grouping (a main hydroxyl grouping). Sugars whose names are in italics in Fig. 1.2 are commonly found in plants, almost exclusively in combined forms. Thus, they are nowadays in our diets in combined forms. Only a small amount of d-glucose in the complimentary monosaccharide form (section on Glycosides in this chapter) is present in natural foods (except for honey), and information technology is generally the but free aldose present.

Figure one.two. Relation of the Fischer projection to the Romanoff shorthand projection for l-threose.

d-Glyceraldehyde occurs naturally every bit its O3 phosphate ester. About other natural sugars, including the ubiquitous d-glucose, have the same configuration (D) of their highest-numbered chiral carbon atom (C5 in the case of a hexose). fifty-Sugars are much less numerous and abundant in nature than the D forms. The master 50-sugar constitute in foods is l-arabinose, which occurs in a combined grade in some polysaccharides.

To make a molecular model of a saccharide, two simple rules need to be followed. The first is to consider but ane carbon atom at a time in copying a projected structure such equally a Fischer projection or a Rosanoff construction. The second is to go on in mind that all horizontal bonds in the projected construction are envisioned equally protruding toward you from the carbon atom, whereas vertical bonds are envisioned as protruding away from you.

And then far aldoses (in which the carbonyl unit of measurement of the saccharose group is that of an aldehyde) have been discussed. In some other type of monosaccharide, the carbonyl unit in the saccharose group is a ketone. These sugars are known as ketoses, with the prefix ket- identifying them as having a ketone group. d-Fructose is the prime example of this carbohydrate grouping. d-Fructose is ane of the ii monosaccharide units of the disaccharide sucrose (Chapter 3) (the other being d-glucose) and makes upward ca. 55% of a common commercial high-fructose syrup (Chapter 7) used in soft drinks. Nigh 40% of the carbohydrates of beloved are d-fructose.

d-Fructose is the chief commercial ketose and the simply i of importance in foods. (In the past, d-fructose was chosen both levulose and fruit sugar, simply these designations are rarely used today.) d-Fructose has only 3 chiral carbon atoms (C3, C4, and C5). Thus, in that location are but two3 or 8 ketohexoses. The various ketotetroses, -pentoses, and -hexoses are related to nonchiral dihydroxyacetone. The suffix designating a ketose in systematic carbohydrate nomenclature is –ulose (Table ane.1). In systematic nomenclature, d-fructose is d-arabino-hexulose because its iii chiral carbon atoms have the same configuration equally those in d-arabinose. The Rosanoff project of a ketopentose (pentulose) with the D-threo configuration (that is the configuration of the two chiral carbon atoms in d-threose) is given in Fig. i.3 every bit another demonstration of the nomenclature principle.

Figure i.3. Rosanoff projection of a ketopentose (D-threo-pentulose, "d-xylulose") showing the configurations of the 2 chiral carbon atoms.

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Carbohydrates

Elhadi M. Yahia , ... Luis A. Bello-Perez , in Postharvest Physiology and Biochemistry of Fruits and Vegetables, 2019

9.ii.2 Monosaccharides

Monosaccharides are the simplest carbohydrates since they cannot be hydrolyzed to smaller carbohydrates. Chemically they are aldehydes or ketones possessing two or more hydroxyl groups, and are of import every bit edifice blocks for the synthesis of nucleic acids, as well equally fuel molecules, that is, in glycolysis. Monosaccharides are classified according to iii different characteristics: the location of their carbonyl group, the number of carbon atoms they contain, and their chiral property. If the carbonyl group is an aldehyde, the monosaccharide is an aldose. If the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses and these are the smallest monosaccharides, such as dihydroxyacetone and d- and l-glyceraldehyde. Those composed of four carbon atoms are chosen tetroses, those with 5 carbons are called pentoses, those of six carbons are hexoses, and so on. The nigh of import monosaccharides in fruits and vegetables are the hexoses, glucose and fructose (Fig. 9.i). Other minor monosaccharides include mannose, galactose, xylose, and arabinose. The most commonly detected pentoses are arabinoses and xyloses. Monosaccharides are usually found in the cytosol (cell sap). Their content is very high in some fruits and vegetables such as corn, peas, and sweet potatoes.

Figure 9.1. Basic structures of some monosaccharides, disaccharides, and polysaccharides.

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Gluten and its main food sources and other components of grains that may affect on health

Justine Bold , in Gluten-Related Disorders, 2022

Fermentable oligo-, di-, and monosaccharides and polyols

FODMAPs are a group of short-chain carbohydrates and carbohydrate alcohols that are rapidly fermentable in the human gut and have over the last decade been extensively studied in relation to functional GI disorders such as IBS. FODMAP sensitivity is not considered to be a gluten-related disorder but FODMAPs are considered as some recent studies have claimed FODMAPs (particularly fructans) lie backside some of gluten'due south pathogenicity. This has been discussed in the section on NCGS.

A low FODMAP nutrition is now accepted as one of the most effective dietary therapies for IBS and provides relief for about 75% of patients [77]. Nonetheless, as yet the long-term impact of following a low FODMAP diet for a long period of time is non fully understood; it may, for instance, potentially impact the gut microbiome [78].

FODMAPs include fructose, which is a monosaccharide, lactose a disaccharide, and the oligosaccharides fructans and galactans and too polyols. FODMAPs are found in many foods, including fruits, vegetables, dairy produce and wheat. When FODMAPs are incompletely digested they are fermented past gut bacteria; this produces gas and luminal distension and so appears to crusade some of the main symptoms of IBS such every bit bloating, wind and abdominal pain. Hence symptoms can be triggered by the ingestion of lactose or fructose; there may be visceral hypersensitivity due to the response of the enteric nervous system to luminal distension; gas production due to the fermentation and bowel motility problems owing to the clearance of fluid and gas (Table 3.4).

Table 3.4. Foods containing FODMAPs.

FODMAP Food source
Fructose Dear, apples, mango, pear, watermelon, sugar snap peas, high fructose corn syrup, corn syrup solids
Fructans Artichokes (Globe), artichokes (Jerusalem), asparagus, beetroot, chicory, dandelion leaves, garlic, leek, onion (brown, white, Spanish, onion pulverization), raddicchio lettuce, spring onion (white office), wheat, rye (in large amounts), inulin, fructooligosaccharides
Lactose Milk, ice cream, custard, dairy desserts, condensed and evaporated milk
Galactooligosaccharides (GOS) Legume beans (east.yard., broiled beans, kidney beans, bortolotti beans), lentils, chickpeas
Polyols Apples, apricots, avocado, cherries, longon, lychee, nectarines, pears, plums, prunes, mushrooms, sorbitol (420), mannitol (421), xylitol (967), maltitol (965), and isomalt (953)

Source: From www.shepherdworks.com.au.

A contempo study investigating the long-term impact of the low FODMAP diet has ended that nutritional adequacy is not compromised but recommends dietetic support to patients on a low FODMAP nutrition; nonetheless, at that place were indications that the diet may toll more and can touch on social eating [79] (Fig. three.v).

Figure 3.five. Role of FODMAPs in triggering symptoms of IBS.

 From Muir JG, Varney JE, Ajamian M, Gibson PR. Gluten-free and lowFODMAP sourdoughs for patients with coeliac disease and irritable bowel syndrome: a clinical perspective. Int J Food Microbiol 2019;290:237–46.

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Carbohydrates: Chemistry and Classification

C. Stylianopoulos , in Encyclopedia of Human Diet (Third Edition), 2013

Monosaccharides

Monosaccharides are the simplest form of saccharide and cannot be further hydrolyzed to smaller subunits. Co-ordinate to their chain length, monosaccharides fall into several categories, the more nutritionally important being the pentoses (v-carbon atom skeleton), e.g., ribose, and the hexoses (6-carbon cantlet skeleton), due east.g., glucose.

The presence of asymmetrical carbons in monosaccharides with different functional groups attached gives rise to optical activity. Monosaccharides are optically active, which means that if polarized light is passed through a solution of these compounds, the aeroplane of light will be rotated to the left (levorotatory or l-form) or to the right (dextrorotatory or d-grade). Consequently, similar structures of the aforementioned chemical compound are formed and are called stereoisomers. Monosaccharides of the d-form are nutritionally important because near naturally occurring monosaccharides are d-stereoisomers and metabolic and digestive enzymes are specific for them.

Monosaccharides demonstrate some other type of stereoisomerism due to their formation of cyclic structures. The pentoses form furanose (5-carbon band) and the hexoses form pyranose (vi-carbon band). Cyclization can produce 2 stereoisomers of the α and β configuration, and generally an equilibrium mixture of the directly and the cyclic forms exists in monosaccharide solutions. Figure 1 illustrates d-glucose in its pyranose form in the α and β configuration. The isomerization produces compounds with different properties and has major metabolic importance considering of enzyme specificity for detail stereoisomers.

Figure 1. d-Glucose molecule shown as open concatenation and as a cyclic pyranose ring in the α and β configuration.

The most nutritionally important and abundant monosaccharide is glucose, which is used as the major cell fuel in the human body and can exist establish unbound in body tissues and fluids. Glucose is the building block of several polysaccharides. Galactose and fructose are also used as prison cell fuel. The most important monosaccharides and monosaccharide derivatives and their significance are outlined in Table one.

Table 1. Some nutritionally of import monosaccharides and monosaccharide derivatives

Course Species Significance
Hexoses d-Glucose Major jail cell fuel, unbound in body fluids and tissues, building block of several polysaccharides
d-Fructose Cell fuel, constituent of sucrose
d-Galactose Cell fuel, elective of galactose
d-Mannose Elective of plant cell wall polysaccharides and gums
Pentoses l-Arabinose, d-xylose Constituent of plant cell wall polysaccharides
d-Ribulose, d-xylulose Metabolite in pentose pathway
d-Ribose RNA constituent
Uronic acids d-Glucuronic, d-galacturonic Constituent of found cell wall polysaccharides
d-Mannuronic, d-guluronic Constituent of algal polysaccharides
Sugar alcohols d-Glucitol, d-xylitol Food ingredient
d-Galactitol Metabolite of galactose
Desoxysugars d-Desoxyribose DNA constituent
d-Desoxygalactose Constituent of algal polysaccharides
l-Fucose Constituent of bacterial polysaccharides
fifty-Rhamnose Constituent of pectic plant polysaccharides
Aminosugars d-Glucosamine, d-galactosamine Constituent of aminosaminoglycans, cartilage

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Carbohydrates From Seaweeds

V. Stiger-Pouvreau , ... Eastward. Deslandes , in Seaweed in Health and Disease Prevention, 2016

Monosaccharides and Disaccharides

Monosaccharides are classified according to iii different characteristics: the position of the carbonyl group, the number of carbon atoms, and its chiral handedness. The monosaccharide is an aldose when the carbonyl grouping is an aldehyde (RCOH), just is a ketose when the carbonyl group is a ketone (RCO). Depending on the number of carbon atoms, the monosaccharides are known as trioses, tetroses, pentoses, hexoses, etc. Both the aldehyde and the ketone group of a straight-chain monosaccharide can react reversibly with a hydroxyl group on a different carbon atom to course a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with v and six atoms are called furanose and pyranose forms, respectively. Heterocyclic band and the direct-concatenation forms be in equilibrium.

Detailed investigations on the hydrolysates of some brown algae accept revealed circuitous mixtures of monosaccharides. The components of galactose, glucose, mannose, fructose, xylose, fucose, and arabinose were found in the total sugars of the hydrolysates. The glucose content was institute to be 65%, 30%, and 20% of the total sugars in an fall sample of 50 individual plants of Saccharina, Fucus (Fucus serratus and Fucus spiralis), and Ascophyllum, respectively (Jensen, 1956). Disaccharide is a carbohydrate, which is formed when two monosaccharides undergo a condensation reaction, with the emptying of a single molecule of HiiO, from the functional groups. Similar monosaccharides, disaccharides form an aqueous solution when dissolved in water. Sucrose is an example of a disaccharide, formed past the combination of glucose and fructose molecules.

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Chemical components and nutrition

Kurt A. Rosentrater , A.D. Evers , in Kent's Technology of Cereals (Fifth Edition), 2018

4.2.1 Monosaccharides

Monosaccharides are the simplest carbohydrates; most of them are sugars. Monosaccharides may take between three and 8 carbon atoms, but only those with five carbons (pentoses) and vi carbons (hexoses) are common. Both pentoses and hexoses exist in a number of isomeric forms – they may be polyhydroxyaldehydes or polyhydroxyketones. Structurally they occur in ring form, which may be six-membered (pyranose grade) or five-membered (furanose form).

In mature cereal grains the monomers are of little importance in their own right, only as components of polymers they are of extreme importance in their contribution to both the structural and storage components of the grain and the behaviour of grains and their products during processing. In this context the most of import monosaccharide, because of its abundance, is the six-carbon polyhydroxyaldehyde d-glucose. It is the monomeric unit of starch, cellulose and β-d-glucans.

The virtually important pentoses are the polyhydroxyaldehydes d-xylose and l-arabinose, because of their contribution to cell wall polymers. The structures of these compounds and of some other monosaccharides institute in cereals are shown in Fig. iv.i.

Figure 4.1. Structural representations of (1) xylose (β-d-xylopyranose), (2) arabinose (α-fifty-arabinofursnose), (3) glucose (β-d-glucopyranose), (4) fructose (β-d-fructofuranose), (five) d-galacturonic acid, (half-dozen) ribose (β-d-ribofuranose), (seven) deoxyribose (β-d-deoxyribofuranose) and (8) mannose (α-d-manno-pyranose).

The near abundant derivatives of monosaccharides are those in which the reducing group forms a glycosidic link with the hydroxyl group of some other organic compound (as in Fig. four.ii), frequently another molecule of the aforementioned species or another monosaccharide. Saccharide molecules may be joined to form short or long bondage past series of glycosidic links, thus producing oligosaccharides or polysaccharides.

Figure four.ii. Formation of the glycosidic link.

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Handbook of Modern Pharmaceutical Analysis

Yin Luo , ... John Steckert , in Separation Science and Engineering, 2011

iv Monosaccharide Limerick Analysis

Monosaccharide composition analysis is ofttimes done to detect the presence of uncommon or singular monosaccharides that may be present on the protein backbone, frequently in O- or C-linked forms. Typically, monosaccharides are released in strong acid at high temperature. 87 Nevertheless, it must be noted that hexose linkages are normally more stable to heat and strong acid than those of fucose or sialic acids. For example, sialic acids are known to decompose after prolonged exposure to heat and acrid. Optimizing the release of monosaccharides crave careful sample training, and if possible, removal of all trace of exogeneous sugars, either by dialysis or buffer exchange with spin columns.

Afterward acid hydrolysis, the released monosaccharides are analyzed on liquid column chromatography or CE. Underivatized monosaccharides may be directly analyzed using HPAEC-PAD or ion-moderated partition chromatography (e.yard., Supelcogel Lead or Bio-Rad Aminex). Analysis of ii-AA or 2-AB derivatized monosaccharides may be done on reversed-stage or anion-exchange chromatography with online fluorescence detection. APTS-labeled monosaccharide analysis is done on the CE with LIF detection. Given the many orthogonal analytical methods that are used to characterize the biotherapeutic glycoprotein, forth with the inherent variability of analysis, the utilise of monosaccharide composition analysis as a drug substance or product release assay has been drastically curtailed.

Sialic acrid assay is typically practical to sialylated glycoproteins which oligosaccharides are shown to affect the pharmacokinetics or biological activity of the biotherapeutic. 88 It is as well a surrogate product attribute mark in bioprocess manufacturing consistency cess. Upward to lxxx different forms of sialic acids are present in nature. 89 Depending on the expression host and jail cell culture weather condition, the most common mammalian sialic acid forms are N-acetylneuraminic acid and North-glycolylneuraminic acid. Both forms may be further modified with O-acetylation, sulfation, or methylation by the expression host‐cell. Dissimilar other monosaccharide linkages, sialic acid glycosidic linkages are highly labile to mild acid and heat treatment. Equally such the sialic acid assay is oftentimes done separately from monosaccharide limerick analysis. Sialidases with specific specificity for certain linkages may be used to release sialic acids and thereby determine the glycosidic linkage. Still, care must be taken as substrate accessibility may be hindered by the poly peptide backbone, and the substrate specificity affected by O-acetylation.

Once released, sialic acids may be analyzed in its underivatized form past HPAEC-PED or derivatized with DMB (1,2-diamino-4,v-methylenedioxybenzene) 90 or OPD(O-phenylene diamine) 91 followed by reversed-phase chromatography with fluorescence detection. If detection and quantification of O-acetylated forms are required HPAEC is non recommended every bit deacetylation volition occur in alkaline metal conditions. In our experience, the DMB method is highly sensitive, robust, and the chromatographic conditions are amenable to online MS analysis.

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Selection of Materials for Microencapsulation

Niraj Vasisht , in Microencapsulation in the Nutrient Industry, 2014

sixteen.four.2 Carbohydrates

Among the class of hydrophilic matrices used in the field of microencapsulation, carbohydrates are the well-nigh commonly used material. Carbohydrates are classified into iv categories: simple sugars or monosaccharides , such equally glucose and fructose, disaccharides, such equally sucrose and lactose, oligosaccharides, such as maltodextrin and dextrins, and polysaccharides, such as starches and cellulose. While all carbohydrate types can be used as fillers and additives, the longer chained saccharides are considered suitable every bit a wall matrix. Polysaccharides are more often than not considered in this class of materials. Polysaccharides likewise include modified starches, where the polysaccharide is structurally and compositionally modified to offer unique solubility, partitioning, and bulwark properties to the agile food ingredient.

Monosaccharides and disaccharides offering both low viscosity in solution and an effective means of flavor microencapsulation. However, they do not offer ability to emulsify the flavor oils. As a event, smaller amounts of stabilizing colloids are used in synergy (Huang, 2012). Past nature of the molecular size, mono- and disaccharides are smaller and readily fit into the interstitial space to prevent formation of a crystallization or crystalline grain boundary within a polysaccharide, which allows for greater stability of the microencapsulated flavour. It is well established that entrapment of season oils in an baggy state offers greater stability than matrices with crystallinity. Therefore, low-molecular-weight mono- and disaccharides are often used with polymer material that inherently exhibits crystalline characteristics. The key properties of carbohydrates that are exploited for the purposes of microencapsulation are:

1.

Gel point

2.

Lower or upper critical solution temperature.

Annotation that mutual carbohydrates that exhibit gel points include agar, agarose, carrageenan, pectin, guar gum, and Konjac®, all of which are considered equally an culling option to gelatin. Critical solution temperature is a property of polymer solution where miscibility is defined. Figure 16.5 depicts the characteristics of critical solution temperatures. The lower critical solution temperature (LCST) is the critical temperature below which the components of a mixture are completely miscible for all compositions. At temperatures below LCST, the system is completely miscible in all proportions, whereas above LCST partial liquid miscibility occurs. Similarly, the upper critical solution temperature (UCST) is the temperature in a higher place which consummate miscibility occurs. Certain celluloses such as hydroxypropyl cellulose testify LCST characteristics. At temperatures greater than twoscore°C, the hydroxypropyl cellulose phase separates in solution. This property is used both for release and cosmos of microcapsules. Similarly, methyl cellulose has an LCST between 40 and 50°C. At temperatures below the LCST, it is readily soluble in water; in a higher place the LCST, it is not soluble, which has a paradoxical effect whereby heating a saturated solution of methyl cellulose will plow it solid, because the methyl cellulose will precipitate out.

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Carbohydrates: Regulation of Metabolism

C. Stylianopoulos , in Encyclopedia of Man Nutrition (Tertiary Edition), 2013

Transport

Monosaccharides traverse the epithelial lining of the intestine past facilitated diffusion or by active transport. The transport system for the passage of glucose and galactose through the apical membrane of the intestinal villi is chosen the sodium (Na +)-dependent glucose transporter (Glut). Fructose utilizes a different transporter for the same passage, called GLUT5. All monosaccharides are then transported from the enterocyte to the bloodstream through another carbohydrate transporter known equally GLUT2. The passage of glucose and galactose across both membranes of the intestine requires the presence of Na+, whereas the passage of fructose is not dependent on Na+ simply on fructose concentration.

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Mass Spectral Analysis of Carbohydrates

Michael A. Madson , in Mass Spectrometry, 2016

2 Component Monosaccharide Analysis by Acid Catalyzed Hydrolysis of Glycan and Qualitative Chromatographic Identification by HPLC

The monosaccharide composition of the glycan to be analyzed is achieved by known methods. More often than not, the glycan to be analyzed is hydrolyzed with stiff acid past HCl solution at various concentrations of acid, diverse times and diverse temperatures due to the varied acid labilities and stabilities of the oligosaccharides and monosaccharides to be analyzed. Ii different hydrolytic weather [4–6] are used for the monosaccharide composition of bovine thyroglobulin O-linked oligosaccharide [4–six] and are shown beneath. The resulting Loftier Performance Anion Exchange Chromatography-Pulsed Amperometric Detection (HPAEC-PAD) chromatograms are shown too [ane,2].

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