In chemistry, a glycosidic bond is a certain type of functional group that joins a carbohydrate (sugar) molecule to another, which may be another carbohydrate. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most In specific terms, a glycosidic bond is formed between the hemiacetal group of a saccharide (or a molecule derived from a saccharide) and the hydroxyl group group of some organic compound such as an alcohol. Hemiacetals and hemiketals are compounds of the general formula R1R2C(OHOR3 where R3 is not a hydrogen Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon In the literature, the bond between an amino group or other nitrogen-containing group and the sugar is often referred to as a glycosidic bond (although IUPAC seems to suggest that the term is a misnomer). Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. For example, the sugar-base bond in a nucleoside may be referred to as a glycosidic bond (e. See also Adenosine triphosphate (ATP g. , Andre and Guschlbauer 1974). A substance containing a glycosidic bond is a glycoside.

Glucose and ethanol combine to form ethyl glucoside and water. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. A glucoside is a Glycoside that is derived from Glucose. Glucosides are common in plants but rare in animals Water is a common Chemical substance that is essential for the survival of all known forms of Life.

Chemistry

The hemiacetal group of carbohydrates (which contains the anomeric carbon) is reactive, and glycosidic bonds form readily in the presence of acid. Hemiacetals and hemiketals are compounds of the general formula R1R2C(OHOR3 where R3 is not a hydrogen In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are This is a condensation reaction as one molecule of water is released. A condensation reaction is a Chemical reaction in which two Molecules or moieties ( Functional groups) combine to form one single molecule together with Water is a common Chemical substance that is essential for the survival of all known forms of Life. Glycosidic bonds are fairly stable; they can be broken chemically by strong aqueous acids. Water is a common Chemical substance that is essential for the survival of all known forms of Life.

A glycosidic functional group is an example of an acetal. An acetal is a Molecule with two single bonded oxygens attached to the same carbon atom

Saccharides in aqueous solution can exist in linear (rare) or cyclic form (more common), and these forms readily interconvert. Only the cyclic forms have an anomeric carbon and can form a glycosidic bond; once the bond has formed, the saccharide unit can no longer attain the linear form.

Polysaccharides

A glycosidic bond can join two monosaccharide molecules to form a disaccharide, as, for instance, in the linkage of glucose and fructose to create sucrose. Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three Solubility of Pure SucroseTemperature(Cg More complicated polysaccharides such as starch, glycogen, cellulose or chitin consist of numerous monosaccharide units joined by glycosidic bonds. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine

While the cyclic structures of monosaccharide units are fairly rigid, the glycosidic bonds confer flexibility to polysaccharide molecules.

Glycosidic bonds join monosaccharides to form polysaccharides, just like peptide bonds join amino acids to form proteins. A peptide bond is a Chemical bond formed between two Molecules when the Carboxyl group of one molecule reacts with the In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl

S-, N-, C-, and O-glycosidic bonds

Adenosine, a component of RNA, results from the sugar ribose and adenine via the formation of an N-glycosidic bond (shown as the vertical line between the N and the sugar cycle)

In analogy, one also considers S-glycosidic bonds, where the anomeric carbon of a sugar is bound to some other group via a sulfur (rather than an oxygen) atom, and N-glycosidic bonds, where the anomeric carbon is bound to some other group via a nitrogen atom. Adenosine is a Nucleoside composed of a Molecule of Adenine attached to a Ribose sugar molecule ( Ribofuranose) moiety via a β-N9- Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Ribose (ɹˈaɪbəʊs ɹˈaɪbəɹʊs primarily seen as D-ribose, is an Aldopentose — a Monosaccharide containing five Carbon Adenine is a Purine with a variety of roles in Biochemistry including Cellular respiration, in the form of both the energy-rich Adenosine In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 The glycosidic bonds discussed earlier are often called O-glycosidic bonds to distinguish them from S- and N-glycosidic bonds. Substances containing N-glycosidic bonds are also known as glycosylamines; the term "N-glycoside" is considered a misnomer by IUPAC and is discouraged. Glycosylamine is a biochemical compound consisting of an Amine with a β-N-glycosidic bond to a Carbohydrate. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization

There is also a C-glycosidic bond which is simply a covalent bond between a sugar and an aglycon. This type is very resistant to hydrolysis.

α-, β-, 1,4 and 1,6 glycosidic bonds

In general, one distinguishes between α- and β-glycosidic bonds, depending on whether the substituent groups on the carbons flanking the ring oxygen are pointing in the same or opposite directions in the standard way of drawing sugars. An α-glycosidic bond for a D-sugar emanates below the plane of the sugar, whereas the hydroxyl (or other substituent group) on the other carbon points above the plane (opposite configuration), while a β-glycosidic bond emanates above that plane (the and pharmacists) often join substances to glucuronic acid via glycosidic bonds in order to increase their water solubility; this is known as glucuronidation. Glucuronic acid (from Greek γλυκερός - "sweet" is a Carboxylic acid. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Glucuronic acid (from Greek γλυκερός - "sweet" is a Carboxylic acid. Many other glycosides have important physiological functions.

Enzymes

Enzymes that break glycosidic bonds (i. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins e. , that catalyze their hydrolysis) are called glycoside hydrolases (or glycosidases). Glycoside hydrolases (also called glycosidases) catalyze the Hydrolysis of the Glycosidic linkage to generate two smaller Sugars They

Glycoside hydrolases typically can act either on α- or on β-glycosidic bonds, but not on both.

Before monosaccharide units are incorporated into glycoproteins, polysaccharides, or lipids in living organisms, they are typically first "activated" by being joined via a glycosidic bond to the phosphate group of a nucleotide such as uridine diphosphate (UDP), guanosine diphosphate (GDP), thymidine diphosphate (TDP), or cytosine monophosphate (CMP). Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Nucleotides are Organic compounds that consist of three joined structures a nitrogenous base a Sugar, and a Phosphate group Uridine diphosphate, abbreviated UDP, is a Nucleotide. It is an Ester of Pyrophosphoric acid with the Nucleoside Uridine Guanosine diphosphate, abbreviated GDP, is a Nucleotide. It is an Ester of Pyrophosphoric acid with the Nucleoside Guanosine Thymidine diphosphate, abbreviated TDP, is a Nucleotide. It is an Ester of Pyrophosphoric acid with the Nucleoside Thymidine Sometimes mono- or oligosaccharides are also activated by being linked to lipids through a phosphate or diphosphate group. These activated species are known as sugar donor substrates. Then enzymes known as glycosyltransferases transfer the sugar unit from the activated glycosyl donor to an accepting nucleophile (the acceptor substrate). Glycosyltransferases are Enzymes ( EC 24) that act as a Catalyst for the transfer of a Monosaccharide unit from an activated sugar Phosphate In Chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a Reagent that forms a Chemical bond to

External links

• Definition of glycosides, from the IUPAC Compendium of Chemical Terminology, the "Gold Book"

References

• Varki A et al. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization Compendium of Chemical Terminology (ISBN 0-86542-684-8 is a book published by IUPAC containing internationally accepted definitions for terms in Chemistry. Essentials of Glycobiology. Cold Spring Harbor Laboratory Press; 1999. [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=glyco.TOC&depth=10 Searchable online
• Andre A and Guschlbauer W. Nucleic Acids Res. 1974 Jun;1(6):803-7. Nucleoside conformations. 15. Flexibility of natural pyrimidine nucleosides around the glycosidic bond.