Maltose

Last updated
Maltose
Maltose2.svg
α-Maltose
Maltose structure.svg
β-Maltose
Names
IUPAC name
(3R,4R,5S,6R)-6-(hydroxymethyl)-5-{[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}oxane-2,3,4-triol
Other names
4-O-α-D-Glucopyranosyl-D-glucose
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.651
EC Number 200-716-5
PubChem CID
UNII
Properties [1]
C12H22O11
Molar mass 342.30 g·mol−1
AppearanceWhite powder or crystals
Density 1.54 g/cm3
Melting point 160 to 165 °C (320 to 329 °F; 433 to 438 K)(anhydrous)
102–103 °C (monohydrate)
1.080 g/mL (20 °C)
+140.7° (H2O, c = 10)
Hazards
Safety data sheet External MSDS
Related compounds
Related
Sucrose
Lactose
Trehalose
Cellobiose
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Amylase reaction consisting of hydrolyzing amylose, producing maltose Amylase reaction.png
Amylase reaction consisting of hydrolyzing amylose, producing maltose

Maltose ( /ˈmɔːlts/ [2] or /ˈmɔːltz/ [3] ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two-unit member of the amylose homologous series, the key structural motif of starch. When beta-amylase breaks down starch, it removes two glucose units at a time, producing maltose. An example of this reaction is found in germinating seeds, which is why it was named after malt. [4] Unlike sucrose, it is a reducing sugar. [5]

Disaccharide complex sugars, the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage; soluble in water; one of the four chemical groupings of carbohydrates

A disaccharide is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose, and maltose.

Glucose A simple form of sugar

Glucose (also called dextrose) is a simple sugar with the molecular formula C6H12O6. Glucose is the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. There it is used to make cellulose in cell walls, which is the most abundant carbohydrate. In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is partially stored as a polymer, in plants mainly as starch and amylopectin and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form of glucose is D-glucose, while L-glucose is produced synthetically in comparably small amounts and is of lesser importance.

In chemistry, a glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.

Contents

History

Maltose was 'discovered' by Augustin-Pierre Dubrunfaut, although this discovery was not widely accepted until it was confirmed in 1872 by Irish chemist and brewer Cornelius O'Sullivan. [5] [6] Its name comes from malt, combined with the suffix '-ose' which is used in names of sugars. [4]

Augustin-Pierre Dubrunfaut was a French chemist.

Cornelius O'Sullivan, FRS was an Irish brewer's chemist.

The suffix -ose is used in biochemistry to form the names of sugars. This Latin suffix means "full of", "abounding in", "given to", or "like". Numerous systems exist to name specific sugars more descriptively.

Maltose making and use in China goes as far back as the Shang dynasty. In Japan, the use of maltose has been recorded since the period of Emperor Jimmu.

Shang dynasty kingdom of ancient China

The Shang dynasty or Yin dynasty, according to traditional historiography, ruled in the Yellow River valley in the second millennium BC, succeeding the Xia dynasty and followed by the Zhou dynasty. The classic account of the Shang comes from texts such as the Book of Documents, Bamboo Annals and Records of the Grand Historian. According to the traditional chronology based on calculations made approximately 2,000 years ago by Liu Xin, the Shang ruled from 1766 to 1122 BC, but according to the chronology based upon the "current text" of Bamboo Annals, they ruled from 1556 to 1046 BC. The Xia–Shang–Zhou Chronology Project dated them from c. 1600 to 1046 BC.

Emperor Jimmu Emperor of Japan

Emperor Jimmu was the first Emperor of Japan, according to legend. His accession is traditionally dated as 660 BC. According to Japanese mythology, he is a descendant of the sun goddess Amaterasu, through her grandson Ninigi, as well as a descendant of the storm god Susanoo. He launched a military expedition from Hyuga near the Seto Inland Sea, captured Yamato, and established this as his center of power. In modern Japan, Jimmu's accession is marked as National Foundation Day on February 11.

Structure and nomenclature

Maltose is a disaccharide: the carbohydrates are generally divided into monosaccharides, oligosaccharides, and polysaccharides depending on the number of sugar subunits. Maltose, with two sugar units, is an oligosaccharide, specifically a disaccharide, because it consists of two glucose molecules. Glucose is a hexose: a monosaccharide containing six carbon atoms. The two glucose units are in the pyranose form and are joined by an O-glycosidic bond, with the first carbon (C1) of the first glucose linked to the fourth carbon (C4) of the second glucose, indicated as (1→4). The link is characterized as α because the glycosidic bond to the anomeric carbon (C1) is in the opposite plane from the CH
2
OH
substituent in the same ring (C6 of the first glucose). If the glycosidic bond to the anomeric carbon (C1) were in the same plane as the CH
2
OH
substituent, it would be classified as a β(1→4) bond, and the resulting molecule would be cellobiose. The anomeric carbon (C1) of the second glucose molecule, which is not involved in a glycosidic bond, could be either an α- or β-anomer depending on the bond direction of the attached hydroxyl group relative to the CH
2
OH
substituent of the same ring, resulting in either α-maltose or β-maltose.

Monosaccharides, also called simple sugars, are the simplest form of sugar and the most basic units of carbohydrates. They cannot be further hydrolyzed to simpler chemical compounds. The general formula is C
n
H
2n
O
n
. They are usually colorless, water-soluble, and crystalline solids. Some monosaccharides have a sweet taste.

An oligosaccharide is a saccharide polymer containing a small number of monosaccharides. Oligosaccharides can have many functions including cell recognition and cell binding. For example, glycolipids have an important role in the immune response.

Polysaccharide polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic linkages and on hydrolysis give the constituent monosaccharides or oligosaccharides

Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic linkages, and on hydrolysis give the constituent monosaccharides or oligosaccharides. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.

An isomer of maltose is isomaltose. This is similar to maltose but instead of a bond in the α(1→4) position, it is in the α(1→6) position, the same bond that is found at the branch points of glycogen and amylopectin.

In chemistry, isomers are ions or molecules with identical formulas but distinct structures. Isomers do not necessarily share similar properties. Two main forms of isomerism are structural isomerism and stereoisomerism.

Isomaltose chemical compound

Isomaltose is a disaccharide similar to maltose, but with a α-(1-6)-linkage instead of the α-(1-4)-linkage. Both of the sugars are glucose, which is a pyranose sugar. Isomaltose is a reducing sugar. Isomaltose is produced when high maltose syrup is treated with the enzyme transglucosidase (TG) and is one of the major components in the mixture isomaltooligosaccharide.

Glycogen polysaccharide

Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.

Properties

Like glucose, maltose is a reducing sugar, because the ring of one of the two glucose units can open to present a free aldehyde group; the other one cannot because of the nature of the glycosidic bond. Maltose can be broken down to glucose by the maltase enzyme, which catalyses the hydrolysis of the glycosidic bond.

Reducing sugar

A reducing sugar is any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. All monosaccharides are reducing sugars, along with some disaccharides, oligosaccharides, and polysaccharides. The monosaccharides can be divided into two groups: the aldoses, which have an aldehyde group, and the ketoses, which have a ketone group. Ketoses must first tautomerize to aldoses before they can act as reducing sugars. The common dietary monosaccharides galactose, glucose and fructose are all reducing sugars.

Aldehyde organic compound containing a functional group with the structure −CHO, consisting of a carbonyl center (a carbon double-bonded to oxygen) with the carbon atom also bonded to hydrogen and to an R group, which is any generic alkyl or side chain

An aldehyde is an organic compound containing a functional group with the structure −CHO, consisting of a carbonyl center with the carbon atom also bonded to hydrogen and to an R group, which is any generic alkyl or side chain. The group—without R—is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry, and many fragrances are aldehydes.

Maltase enzyme

Maltase is an enzyme located in on the brush border of the small intestine that breaks down the disaccharide maltose. Maltase catalyzes the hydrolysis of maltose to the simple sugar glucose. This enzyme is found in plants, bacteria, and yeast. Acid maltase deficiency is categorized into three separate types based on the age of onset of symptoms in the affected individual.

Maltose in aqueous solution exhibits mutarotation, because the α and β isomers that are formed by the different conformations of the anomeric carbon have different specific rotations, and in aqueous solutions, these two forms are in equilibrium.

It has a sweet taste, but is only about 30-60% as sweet as sugar, depending on the concentration. [7] A 10% solution of maltose is 35% as sweet as sucrose. [8]

Sources and absorption

Maltose syrup Maltose syrup.jpg
Maltose syrup

Maltose is a component of malt, a substance which is obtained in the process of allowing grain to soften in water and germinate. It is also present in highly variable quantities in partially hydrolysed starch products like maltodextrin, corn syrup and acid-thinned starch. [9]

In humans, maltose is broken down by various maltase enzymes, providing two glucose molecules which can be further processed: either broken down to provide energy, or stored as glycogen. The lack of the sucrase-isomaltase enzyme in humans causes sucrose intolerance, but because there are four different maltase enzymes, complete maltose intolerance is extremely rare. [10]

Related Research Articles

Carbohydrate organic compound that consists only of carbon, hydrogen, and oxygen

A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula Cm(H2O)n (where m may be different from n). This formula holds true for monosaccharides. Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. The carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as aldoses and ketoses.

Hydrolysis is a term used for both an electro-chemical process and a biological one. The hydrolysis of water is the separation of water molecules into hydrogen and oxygen atoms using electricity (electrolysis).

Starch carbohydrate consisting of a large number of glucose units joined by glycosidic bonds

Starch or amylum is a polymeric carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants as energy storage. It is the most common carbohydrate in human diets and is contained in large amounts in staple foods like potatoes, wheat, maize (corn), rice, and cassava.

Fructose A simple ketonic monosaccharide found in many plants

Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into blood during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847. The name "fructose" was coined in 1857 by the English chemist William Allen Miller. Pure, dry fructose is a sweet, white, odorless, crystalline solid, and is the most water-soluble of all the sugars. Fructose is found in honey, tree and vine fruits, flowers, berries, and most root vegetables.

Sucrose chemical compound

Sucrose is common sugar. It is a disaccharide, a molecule composed of two monosaccharides: glucose and fructose. Sucrose is produced naturally in plants, from which table sugar is refined. It has the molecular formula C12H22O11.

Amylase enzyme

Amylase is an enzyme that catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of starch but little sugar, such as rice and potatoes, may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar. The pancreas and salivary gland make amylase to hydrolyse dietary starch into disaccharides and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. As diastase, amylase is the first enzyme to be discovered and isolated. Specific amylase proteins are designated by different Greek letters. All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds.

Glycoside molecule in which a sugar is bound to another functional group

In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of Heliconius butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.

Mashing heating grain and water into mash

In brewing and distilling, mashing is the process of combining a mix of grains – typically malted barley with supplementary grains such as corn, sorghum, rye, or wheat – known as the "grain bill" with water and then heating the mixture. Mashing allows the enzymes in the malt to break down the starch in the grain into sugars, typically maltose to create a malty liquid called wort. The two main methods of mashing are infusion mashing, in which the grains are heated in one vessel, and decoction mashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature. Mashing involves pauses at certain temperatures and takes place in a "mash tun" – an insulated brewing vessel with a false bottom.

Trehalose chemical compound

Trehalose is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it as a source of energy, and to survive freezing and lack of water.

Glucose 1-phosphate chemical compound

Glucose 1-phosphate is a glucose molecule with a phosphate group on the 1'-carbon. It can exist in either the α- or β-anomeric form.

Carbohydrase is a set of enzymes that catalyzes 5 types of breakdown during carbohydrates into simple sugars.

Anomeric effect stereoelectronic effect, tendency of heteroatomic substituents adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation instead of the less hindered equatorial orientation that would be expected from steric considerations

In organic chemistry, the anomeric effect or Edward-Lemieux effect is a stereoelectronic effect that describes the tendency of heteroatomic substituents adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation instead of the less hindered equatorial orientation that would be expected from steric considerations. This effect was originally observed in pyranose rings by J. T. Edward in 1955 when studying carbohydrate chemistry.

Beta-amylase

Beta-amylase is an enzyme with the systematic name 4-alpha-D-glucan maltohydrolase. This enzyme catalyses the following chemical reaction:

Oligosaccharides and polysaccharides are an important class of polymeric carbohydrates found in virtually all living entities. Their structural features make their nomenclature challenging and their roles in living systems make their nomenclature important.

References

  1. Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-367. ISBN   0-8493-0462-8..
  2. Dictionary Reference: maltose
  3. Cambridge dictionary: maltose
  4. 1 2 Stoker, H. Stephen (2015-01-02). Organic and Biological Chemistry. Cengage Learning. ISBN   9781305686458.
  5. 1 2 Fruton, Joseph S (1999). Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology. Chelsea, Michigan: Yale University Press. p. 144. ISBN   0300153597 . Retrieved 21 October 2017.
  6. O'Sullivan, Cornelius (1872). "XXI.?On the transformation-products of starch". Journal of the Chemical Society. 25: 579–588. doi:10.1039/JS8722500579 . Retrieved 11 December 2014.
  7. Belitz, H.-D.; Grosch, Werner; Schieberle, Peter (2009-01-15). Food Chemistry. Springer Science & Business Media. p. 863. ISBN   9783540699330.
  8. Spillane, W. J. (2006-07-17). Optimising Sweet Taste in Foods. Woodhead Publishing. p. 271. ISBN   9781845691646.
  9. Furia, Thomas E. (1973-01-02). CRC Handbook of Food Additives, Second Edition. CRC Press. ISBN   9780849305429.
  10. Whelan, W. J.; Cameron, Margaret P. (2009-09-16). Control of Glycogen Metabolism. John Wiley & Sons. p. 60. ISBN   9780470716885.