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Nucleoside

 

 
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Nucleoside
 
 
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Nucleosides are glycosylamine
Glycosylamine

Glycosylamine is a biochemical compound consisting of an amine with a Glycosidic bond to a carbohydrate thus forming a cyclic hemiaminal ether bond ....
s consisting of a nucleobase
Nucleobase

Nucleobases are the parts of DNA and RNA that may be involved in pairing . The main ones are cytosine, guanine, adenine , thymine and uracil , abbreviated as C, G, A, T, and U, respectively....
 (often referred to simply base) bound to a ribose
Ribose

Ribose, primarily occurring as D-ribose, is an organic compound that occurs widely in nature. It is an aldopentose, that is a monosaccharide containing five carbon atoms that, in its acyclic form, has an aldehyde functional group at one end....
 or deoxyribose
Deoxyribose

Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group in its linear structure....
 sugar
Sugar

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many other sources....
. Examples of these include cytidine
Cytidine

Cytidine is a nucleoside molecule that is formed when cytosine is attached to a ribose ring via a ?-N1-glycosidic bond. Cytidine is a component of RNA....
, uridine
Uridine

Uridine is a molecule that is formed when uracil is attached to a ribose ring via a ?-N1-glycosidic bond.If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine....
, adenosine
Adenosine

Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....
, guanosine
Guanosine

Guanosine is a nucleoside comprising guanine attached to a ribose ring via a ?-N9-glycosidic bond.Guanosine can be phosphorylated to become GMP , cGMP , GDP and GTP ....
, thymidine
Thymidine

Thymidine is a chemical Chemical compound, more precisely a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine in double-stranded DNA....
 and inosine
Inosine

Inosine is a nucleoside that is formed when hypoxanthine is attached to a ribose ring via a ?-N9-glycosidic bond.Inosine is commonly found in tRNAs and is essential for proper translation of the genetic code in wobble base pairs....
.

Nucleosides can be phosphorylated
Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Protein phosphorylation in particular plays a significant role in a wide range of cellular processes....
 by specific kinase
Kinase

In chemistry and biochemistry, a kinase, alternatively known as a phosphotransferase, is a type of enzyme that transfers phosphate groups from High-energy phosphate donor molecules, such as adenosine triphosphate, to specific target molecules ; the process is termed phosphorylation ...
s in the cell on the sugar's primary alcohol group (-CH2-OH), producing nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
s, which are the molecular building blocks of DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 and RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
.

Nucleosides can be produced by de novo synthesis pathways, particularly in the liver, but they are more abundantly supplied via ingestion and digestion of nucleic acids in the diet, whereby nucleotidase
Nucleotidase

A nucleotidase is a hydrolase that catalyzes the hydrolysis of a nucleotide into a nucleoside and a phosphate. For example, they convert adenosine monophosphate to adenosine, and guanosine monophosphate to guanosine....
s break down nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
s (such as the thymine
Thymine

Thymine is one of the four bases in the nucleic acid of DNA that make up the letters GCAT. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine....
 nucleotide) into nucleosides (such as thymidine
Thymidine

Thymidine is a chemical Chemical compound, more precisely a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine in double-stranded DNA....
) and phosphate.






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Nucleosides are glycosylamine
Glycosylamine

Glycosylamine is a biochemical compound consisting of an amine with a Glycosidic bond to a carbohydrate thus forming a cyclic hemiaminal ether bond ....
s consisting of a nucleobase
Nucleobase

Nucleobases are the parts of DNA and RNA that may be involved in pairing . The main ones are cytosine, guanine, adenine , thymine and uracil , abbreviated as C, G, A, T, and U, respectively....
 (often referred to simply base) bound to a ribose
Ribose

Ribose, primarily occurring as D-ribose, is an organic compound that occurs widely in nature. It is an aldopentose, that is a monosaccharide containing five carbon atoms that, in its acyclic form, has an aldehyde functional group at one end....
 or deoxyribose
Deoxyribose

Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group in its linear structure....
 sugar
Sugar

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many other sources....
. Examples of these include cytidine
Cytidine

Cytidine is a nucleoside molecule that is formed when cytosine is attached to a ribose ring via a ?-N1-glycosidic bond. Cytidine is a component of RNA....
, uridine
Uridine

Uridine is a molecule that is formed when uracil is attached to a ribose ring via a ?-N1-glycosidic bond.If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine....
, adenosine
Adenosine

Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....
, guanosine
Guanosine

Guanosine is a nucleoside comprising guanine attached to a ribose ring via a ?-N9-glycosidic bond.Guanosine can be phosphorylated to become GMP , cGMP , GDP and GTP ....
, thymidine
Thymidine

Thymidine is a chemical Chemical compound, more precisely a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine in double-stranded DNA....
 and inosine
Inosine

Inosine is a nucleoside that is formed when hypoxanthine is attached to a ribose ring via a ?-N9-glycosidic bond.Inosine is commonly found in tRNAs and is essential for proper translation of the genetic code in wobble base pairs....
.

Nucleosides can be phosphorylated
Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Protein phosphorylation in particular plays a significant role in a wide range of cellular processes....
 by specific kinase
Kinase

In chemistry and biochemistry, a kinase, alternatively known as a phosphotransferase, is a type of enzyme that transfers phosphate groups from High-energy phosphate donor molecules, such as adenosine triphosphate, to specific target molecules ; the process is termed phosphorylation ...
s in the cell on the sugar's primary alcohol group (-CH2-OH), producing nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
s, which are the molecular building blocks of DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 and RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
.

Nucleosides can be produced by de novo synthesis pathways, particularly in the liver, but they are more abundantly supplied via ingestion and digestion of nucleic acids in the diet, whereby nucleotidase
Nucleotidase

A nucleotidase is a hydrolase that catalyzes the hydrolysis of a nucleotide into a nucleoside and a phosphate. For example, they convert adenosine monophosphate to adenosine, and guanosine monophosphate to guanosine....
s break down nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
s (such as the thymine
Thymine

Thymine is one of the four bases in the nucleic acid of DNA that make up the letters GCAT. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine....
 nucleotide) into nucleosides (such as thymidine
Thymidine

Thymidine is a chemical Chemical compound, more precisely a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine in double-stranded DNA....
) and phosphate. The nucleosides, in turn, are subsequently broken down:

  • in the lumen
    Lumen (anatomy)

    A lumen in biology is the inside space of a tubular structure, such as an artery or intestine. By extension, a lumen can also be the inside space of a cellular component or structure, such as the endoplasmic reticulum....
     of the digestive system by nucleosidases into nucleobases and ribose or deoxyribose.
  • inside the cell into nitrogenous base
    Nitrogenous base

    A nitrogenous base is an organic compound that owes its property as a Base_ to the lone pair of electrons of a nitrogen atom. Notable nitrogenous bases include...
    s, and ribose-1-phosphate or deoxyribose-1-phosphate.


In medicine several nucleoside analogues
Nucleoside analogues

Nucleoside analogues are a range of antiviral products used to prevent viral replication in infected cells. The most commonly used is Aciclovir....
 are used as antiviral or anticancer agents. The viral polymerase incorporates these compounds with non-canonical bases. These compounds are activated in the cells by being converted into nucleotides, they are administered as nucleosides since charged nucleotides cannot easily cross cell membranes.

In molecular biology several analogues
Nucleic acid analogues

Nucleic acid analogues are compounds structurally similar to naturally occurring RNA and DNA, used in medicine and in molecular biology research....
 of the sugar back bone exist. Due to the low stability of RNA, which is prone to hydrolysis, several more stable alternative nucleoside/nucleotide analogues are used which correctly bind to RNA. This is achieved by using a different backbone sugar. These analogues include LNA
LNA

LNA is a three letter acronym that may stand for:...
, morpholino
Morpholino

In molecular biology, a Morpholino is a molecule used to modify gene expression. Morpholino oligomers are an antisense technology used to block access of other molecules to specific sequences within nucleic acid....
, PNA
PNA

Peptide nucleic acid is an artificially synthesized polymer similar to DNA or RNA and is used in biological research and medical treatments. PNA is not known to occur naturally....
.

In sequencing dideoxynucleotides
Dideoxynucleotides

Dideoxynucleotides, or ddNTPs, are nucleotides lacking a 3'-hydroxyl group on their deoxyribose sugar. Since deoxyribose already lacks a 2'-OH, dideoxyribose lacks hydroxyl groups at both its 2' and 3' carbons....
 are used. These nucleotides possess a non-canon sugar, dideoxyribose which lacks 3' hydroxyl group (which accepts the phosphate) and therefore cannot bond with the next base, terminating the chain as DNA polymerases mistake it for a regular deoxyribonucleotide.




See also

  • Adenosine triphosphate
    Adenosine triphosphate

    This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
     (ATP)