Adenosine diphosphate
Overview
 
Adenosine diphosphate, abbreviated ADP, is a nucleoside diphosphate. It is an ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 of pyrophosphoric acid
Pyrophosphoric acid
Pyrophosphoric acid, also known under the name diphosphoric acid, is colorless, odorless, hygroscopic and is soluble in water, diethyl ether, and ethyl alcohol. It is produced from phosphoric acid by dehydration. Pyrophosphoric acid slowly hydrolyzes in the presence of water into phosphoric...

 with the nucleoside
Nucleoside
Nucleosides are glycosylamines consisting of a nucleobase bound to a ribose or deoxyribose sugar via a beta-glycosidic linkage...

 adenosine. ADP consists of the pyrophosphate
Pyrophosphate
In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Any salt or ester containing two phosphate groups is called a diphosphate. As a food additive, diphosphates are known as E450.- Chemistry :...

 group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

, the pentose
Pentose
A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups. Aldopentoses have an aldehyde functional group at position 1...

 sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 ribose
Ribose
Ribose is an organic compound with the formula C5H10O5; specifically, a monosaccharide with linear form H––4–H, which has all the hydroxyl groups on the same side in the Fischer projection....

, and the nucleobase
Nucleobase
Nucleobases are a group of nitrogen-based molecules that are required to form nucleotides, the basic building blocks of DNA and RNA. Nucleobases provide the molecular structure necessary for the hydrogen bonding of complementary DNA and RNA strands, and are key components in the formation of stable...

 adenine
Adenine
Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...

.

ADP is the product of ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

 dephosphorylation
Dephosphorylation
Dephosphorylation is the essential process of removing phosphate groups from an organic compound by hydrolysis. Its opposite is phosphorylation...

 by ATPase
ATPase
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate into adenosine diphosphate and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur...

s. ADP is converted back to ATP by ATP synthase
ATP synthase
right|thumb|300px|Molecular model of ATP synthase by X-ray diffraction methodATP synthase is an important enzyme that provides energy for the cell to use through the synthesis of adenosine triphosphate . ATP is the most commonly used "energy currency" of cells from most organisms...

s. ATP is an important energy transfer molecule in cells.

ADP is stored in dense bodies
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

 inside blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s and is released upon platelet activation.
Encyclopedia
Adenosine diphosphate, abbreviated ADP, is a nucleoside diphosphate. It is an ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 of pyrophosphoric acid
Pyrophosphoric acid
Pyrophosphoric acid, also known under the name diphosphoric acid, is colorless, odorless, hygroscopic and is soluble in water, diethyl ether, and ethyl alcohol. It is produced from phosphoric acid by dehydration. Pyrophosphoric acid slowly hydrolyzes in the presence of water into phosphoric...

 with the nucleoside
Nucleoside
Nucleosides are glycosylamines consisting of a nucleobase bound to a ribose or deoxyribose sugar via a beta-glycosidic linkage...

 adenosine. ADP consists of the pyrophosphate
Pyrophosphate
In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Any salt or ester containing two phosphate groups is called a diphosphate. As a food additive, diphosphates are known as E450.- Chemistry :...

 group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

, the pentose
Pentose
A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups. Aldopentoses have an aldehyde functional group at position 1...

 sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 ribose
Ribose
Ribose is an organic compound with the formula C5H10O5; specifically, a monosaccharide with linear form H––4–H, which has all the hydroxyl groups on the same side in the Fischer projection....

, and the nucleobase
Nucleobase
Nucleobases are a group of nitrogen-based molecules that are required to form nucleotides, the basic building blocks of DNA and RNA. Nucleobases provide the molecular structure necessary for the hydrogen bonding of complementary DNA and RNA strands, and are key components in the formation of stable...

 adenine
Adenine
Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...

.

ADP is the product of ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

 dephosphorylation
Dephosphorylation
Dephosphorylation is the essential process of removing phosphate groups from an organic compound by hydrolysis. Its opposite is phosphorylation...

 by ATPase
ATPase
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate into adenosine diphosphate and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur...

s. ADP is converted back to ATP by ATP synthase
ATP synthase
right|thumb|300px|Molecular model of ATP synthase by X-ray diffraction methodATP synthase is an important enzyme that provides energy for the cell to use through the synthesis of adenosine triphosphate . ATP is the most commonly used "energy currency" of cells from most organisms...

s. ATP is an important energy transfer molecule in cells.

ADP is stored in dense bodies
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

 inside blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s and is released upon platelet activation. ADP interacts with a family of ADP receptors found on platelets (P2Y1, P2Y12
P2Y12
In the field of molecular biology, the P2Y12 protein is found mainly but not only on the surface of blood platelet cells and is an important regulator in blood clotting....

 and P2X1), leading to further platelet activation. ADP in the blood is converted to adenosine by the action of ecto-ADPases, inhibiting further platelet activation via adenosine receptor
Adenosine receptor
The adenosine receptors are a class of purinergic receptors, G protein-coupled receptors with adenosine as endogenous ligand.-Pharmacology:...

s.

ADP is the end-product that results when ATP loses one of its phosphate groups located at the end of the molecule. The conversion of these two molecules plays a critical role in supplying energy for many processes of life. The deletion of one of ATP’s phosphorus bonds generates approximately 7.3 kilocalories per Mole of ATP. ADP can be converted, or powered back to ATP through the process of releasing the chemical energy available in food; in humans this is constantly performed via aerobic respiration in the mitochondria. Plants use photosynthetic pathways to convert and store the energy from sunlight, via conversion of ADP to ATP. Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance.

Single nucleotides (ADP) have the ability to catalyze organic reactions. This has relevance for prebiotic studies of the RNA world hypothesis
RNA world hypothesis
The RNA world hypothesis proposes that life based on ribonucleic acid pre-dates the current world of life based on deoxyribonucleic acid , RNA and proteins. RNA is able both to store genetic information, like DNA, and to catalyze chemical reactions, like an enzyme protein...

 for the origin of life on Earth.

See also

  • Nucleoside
    Nucleoside
    Nucleosides are glycosylamines consisting of a nucleobase bound to a ribose or deoxyribose sugar via a beta-glycosidic linkage...

  • Nucleotide
    Nucleotide
    Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

  • DNA
    DNA
    Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

  • RNA
    RNA
    Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

  • Oligonucleotide
    Oligonucleotide
    An oligonucleotide is a short nucleic acid polymer, typically with fifty or fewer bases. Although they can be formed by bond cleavage of longer segments, they are now more commonly synthesized, in a sequence-specific manner, from individual nucleoside phosphoramidites...

  • Adenosine triphosphate
    Adenosine triphosphate
    Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

  • Adenosine monophosphate
    Adenosine monophosphate
    Adenosine monophosphate , also known as 5'-adenylic acid, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid and the nucleoside adenosine. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine...

  • Apyrase
    Apyrase
    Apyrase is a calcium-activated plasma membrane-bound enzyme that catalyses the hydrolysis of ATP to yield AMP and inorganic phosphate. Two isoenzymes are found in commercial preparations from S. tuberosum...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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