Editing Adenosine diphosphate

{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 477242390
| ImageFile = Adenosindiphosphat protoniert.svg
| ImageSize = 220px
| ImageName = Skeletal formula of ADP
| ImageFile1 = Adenosine-diphosphate-3D-balls.png
| ImageSize1 = 230px
| ImageName1 = Ball-and-stick model of ADP (shown here as a 3- ion)
| IUPACName = Adenosine 5′-(trihydrogen diphosphate)
| SystematicName = [(2''R'',3''S'',4''R'',5''R'')-5-(6-Amino-9''H''-purin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl trihydrogen diphosphate
| OtherNames = Adenosine 5′-diphosphate; Adenosine 5′-pyrophosphate; Adenosine pyrophosphate
|Section1={{Chembox Identifiers
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| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 14830
| InChI = 1/C10H15N5O10P2/c11-8-5-9(13-2-12-8)15(3-14-5)10-7(17)6(16)4(24-10)1-23-27(21,22)25-26(18,19)20/h2-4,6-7,10,16-17H,1H2,(H,21,22)(H2,11,12,13)(H2,18,19,20)/t4-,6-,7-,10-/m1/s1
| InChIKey = XTWYTFMLZFPYCI-KQYNXXCUBP
| SMILES1 = c1nc(c2c(n1)n(cn2)[C@H]3[C@@H]([C@@H]([C@H](O3)COP(=O)(O)OP(=O)(O)O)O)O)N
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C10H15N5O10P2/c11-8-5-9(13-2-12-8)15(3-14-5)10-7(17)6(16)4(24-10)1-23-27(21,22)25-26(18,19)20/h2-4,6-7,10,16-17H,1H2,(H,21,22)(H2,11,12,13)(H2,18,19,20)/t4-,6-,7-,10-/m1/s1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = XTWYTFMLZFPYCI-KQYNXXCUSA-N
| CASNo=58-64-0
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 61D2G4IYVH
| PubChem= 6022
| IUPHAR_ligand = 1712
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 16761
| KEGG_Ref = {{keggcite|changed|kegg}}
| KEGG = C00008
| SMILES = O=P(O)(O)OP(=O)(O)OC[C@H]3O[C@@H](n2cnc1c(ncnc12)N)[C@H](O)[C@@H]3O
| EINECS = 218-249-0
| DrugBank_Ref = {{drugbankcite|changed|drugbank}}
| DrugBank = DB03431
| RTECS = AU7467000
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|Section2={{Chembox Properties
| C=10|H=15|N=5|O=10|P=2
| MolarMass=427.201 g/mol
| Density=2.49 g/mL
| MeltingPt=
| BoilingPtC=
| Solubility=
| LogP = −2.640
  }}
|Section3={{Chembox Hazards
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'''Adenosine diphosphate''' ('''ADP'''), also known as '''adenosine pyrophosphate''' ('''APP'''), is an important [[organic compound]] in [[metabolism]] and is essential to the flow of energy in living [[cells (biology)|cells]]. ADP consists of three important structural components: a [[sugar]] backbone attached to [[adenine]] and two [[phosphate]] groups bonded to the 5 carbon atom of [[ribose]]. The diphosphate group of ADP is attached to the 5’ carbon of the sugar backbone, while the adenine attaches to the 1’ carbon.<ref name=Lehninger>{{cite book |author=Cox, Michael |author2=Nelson, David R. |author3=Lehninger, Albert L |title=Lehninger principles of biochemistry |publisher=W.H. Freeman |location=San Francisco |year=2008 |isbn=978-0-7167-7108-1 |url-access=registration |url=https://archive.org/details/lehningerprincip00lehn_1 }}</ref>

ADP can be interconverted to [[adenosine triphosphate]] (ATP) and [[adenosine monophosphate]] (AMP). ATP contains one more phosphate group than ADP, while AMP contains one fewer phosphate group. Energy transfer used by all living things is a result of [[dephosphorylation]] of ATP by enzymes known as [[ATPase]]s. The cleavage of a phosphate group from ATP results in the coupling of energy to metabolic reactions and a by-product of ADP.<ref name=Lehninger/> ATP is continually reformed from lower-energy species ADP and AMP. The biosynthesis of ATP is achieved throughout processes such as [[substrate-level phosphorylation]], [[oxidative phosphorylation]], and [[photophosphorylation]], all of which facilitate the addition of a phosphate group to ADP.

==Bioenergetics==
ADP cycling supplies the [[energy]] needed to do work in a biological system, the [[thermodynamic]] process of transferring energy from one source to another. There are two types of energy: [[potential energy]] and [[kinetic energy]]. Potential energy can be thought of as stored energy, or usable energy that is available to do work. Kinetic energy is the energy of an object as a result of its motion. The significance of ATP is in its ability to store potential energy within the phosphate bonds. The energy stored between these bonds can then be transferred to do work. For example, the transfer of energy from ATP to the protein [[myosin]] causes a conformational change when connecting to [[actin]] during [[muscle contraction]].<ref name=Lehninger/>

[[File:ATP-ADP.svg|thumb|The cycle of synthesis and degradation of ATP; 1 and 2 represent output and input of energy, respectively.]]It takes multiple reactions between myosin and actin to effectively produce one muscle contraction, and, therefore, the availability of large amounts of ATP is required to produce each muscle contraction. For this reason, biological processes have evolved to produce efficient ways to replenish the potential energy of ATP from ADP.<ref name="hyperphysics.phy-astr.gsu.edu">{{cite web |author =Nave, C.R. |title=Adenosine Triphosphate |year=2005 |work=Hyper Physics [serial on the Internet] |publisher=Georgia State University |url=http://hyperphysics.phy-astr.gsu.edu/hbase/biology/atp.html}}</ref>    

Breaking one of ATP's phosphorus bonds generates approximately 30.5 [[kilojoule]]s per [[Mole (unit)|mole]] of ATP (7.3 [[Calorie|kcal]]).<ref name="emc.maricopa.edu">{{cite web|author=Farabee, M.J. |title=The Nature of ATP |year=2002 |work=ATP and Biological Energy [serial on the Internet] |url=http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookATP.html |url-status=dead |archive-url=https://web.archive.org/web/20071201180511/http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookATP.html |archive-date=2007-12-01 }}</ref> 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 [[mitochondrion|mitochondria]].<ref name="hyperphysics.phy-astr.gsu.edu"/> Plants use [[photosynthetic]] pathways to convert and store energy from sunlight, also conversion of ADP to ATP.<ref name="emc.maricopa.edu"/> 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.<ref name="hyperphysics.phy-astr.gsu.edu"/>

==Cellular respiration==

===Catabolism===
The ten-step [[catabolic]] pathway of [[glycolysis]] is the initial phase of free-energy release in the breakdown of  [[glucose]] and can be split into two phases, the preparatory phase and payoff phase. ADP and [[phosphate]] are needed as precursors to synthesize ATP in the payoff reactions of the [[TCA cycle]] and [[oxidative phosphorylation]] mechanism.<ref>{{cite journal |vauthors =Jensen TE, Richter EA |title=Regulation of glucose and glycogen metabolism during and after exercise |journal=J. Physiol. |volume=590 |issue=Pt 5 |pages=1069–76 |date=March 2012|pmid=22199166 |pmc=3381815 |doi=10.1113/jphysiol.2011.224972 }}</ref>  During the payoff phase of glycolysis, the enzymes phosphoglycerate kinase and pyruvate kinase facilitate the addition of a phosphate group to ADP by way of [[substrate-level phosphorylation]].<ref>{{cite journal |vauthors =Liapounova NA, Hampl V, Gordon PM, Sensen CW, Gedamu L, Dacks JB |title=Reconstructing the mosaic glycolytic pathway of the anaerobic eukaryote Monocercomonoides |journal=Eukaryotic Cell |volume=5 |issue=12 |pages=2138–46 |date=December 2006|pmid=17071828 |pmc=1694820 |doi=10.1128/EC.00258-06 }}</ref>
[[File:Glycolysis overview.svg|thumb|Glycolysis overview]]

===Glycolysis===
{{main|glycolysis}}
Glycolysis is performed by all living organisms and consists of 10 steps.  The net reaction for the overall process of [[glycolysis]] is:<ref>{{cite web|last=Medh|first=J.D|title=Glycolysis|url=http://www.csun.edu/~jm77307/Glycolysis.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.csun.edu/~jm77307/Glycolysis.pdf |archive-date=2022-10-09 |url-status=live|publisher=CSUN.Edu|access-date=3 April 2013}}</ref>
:Glucose + 2 NAD+ + 2 P<sub>i</sub> + 2 ADP → 2 pyruvate + 2 ATP + 2 NADH + 2 H<sub>2</sub>O
Steps 1 and 3 require the input of energy derived from the hydrolysis of ATP to ADP and P<sub>i</sub> (inorganic phosphate), whereas steps 7 and 10 require the input of ADP, each yielding ATP.<ref>{{cite web|last=Bailey|first=Regina|title=10 Steps of Glycolysis|url=http://biology.about.com/od/cellularprocesses/a/aa082704a.htm|access-date=2013-05-10|archive-date=2013-05-15|archive-url=https://web.archive.org/web/20130515102637/http://biology.about.com/od/cellularprocesses/a/aa082704a.htm|url-status=dead}}</ref>  The [[enzyme]]s necessary to break down glucose are found in the [[cytoplasm]], the viscous fluid that fills living cells, where the glycolytic reactions take place.<ref name=Lehninger/>

===Citric acid cycle===
{{main|citric acid cycle}}
The [[citric acid cycle]], also known as the Krebs cycle or the TCA (tricarboxylic acid) cycle is an 8-step process that takes the pyruvate generated by glycolysis and generates 4 NADH, FADH2, and GTP, which is further converted to ATP.<ref>{{cite web|title=Citric Acid Cycle |url=http://web.ku.edu/~crystal/taksnotes/Biol_638/notes/chp_16.pdf |publisher=Takusagawa’s Note |access-date=4 April 2013 |url-status=dead |archive-url=https://web.archive.org/web/20120324072437/http://web.ku.edu/~crystal/taksnotes/Biol_638/notes/chp_16.pdf |archive-date=24 March 2012 }}</ref> It is only in step 5, where GTP is generated, by succinyl-CoA synthetase, and then converted to ATP, that ADP is used (GTP + ADP → GDP + ATP).<ref>{{cite web|title=Biochemistry |url=http://www.uccs.edu/~sbraunsa/Images/482Notes/17-TCAcycle.pdf |publisher=UCCS.edu |url-status=dead |archive-url=https://web.archive.org/web/20130228175004/http://www.uccs.edu/~sbraunsa/Images/482Notes/17-TCAcycle.pdf |archive-date=2013-02-28 }}</ref>
<!-- Deleted image removed: [[File:Conversion of GTP to ATP.jpg|thumbnail|chemical conversion of GTP to ATP]] -->

===Oxidative phosphorylation===
{{main|oxidative phosphorylation}}
[[Oxidative phosphorylation]] produces 26 of the 30 equivalents of ATP generated in cellular respiration by transferring electrons from NADH or FADH2 to [[Oxygen|O<sub>2</sub>]] through electron carriers.<ref>{{cite web|title=Oxidative phosphorylation|url=https://www.ncbi.nlm.nih.gov/books/NBK21208/|publisher=W H Freeman, 2002|access-date=4 April 2013}}</ref> The energy released when electrons are passed from higher-energy NADH or FADH2 to the lower-energy O<sub>2</sub> is required to phosphorylate ADP and once again generate ATP.<ref>{{cite web|last=Medh|first=J. D.|title=Electron Transport Chain (Overview)|url=http://www.csun.edu/~jm77307/Oxidative%20Phosphorylation.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.csun.edu/~jm77307/Oxidative%20Phosphorylation.pdf |archive-date=2022-10-09 |url-status=live|publisher=CSUN.edu|access-date=4 April 2013}}</ref> It is this energy coupling and phosphorylation of ADP to ATP that gives the electron transport chain the name oxidative phosphorylation.<ref name=Lehninger/>
[[File:ATP-Synthase.svg|thumb|ATP-Synthase]]

====Mitochondrial ATP synthase complex====
{{main|ATP synthase}}
During the initial phases of [[glycolysis]] and the [[TCA cycle]], [[cofactor (biochemistry)|cofactors]] such as [[NAD+]] donate and accept electrons<ref>{{cite journal |vauthors =Belenky P, Bogan KL, Brenner C |title=NAD+ metabolism in health and disease |journal=Trends Biochem. Sci. |volume=32 |issue=1 |pages=12–9 |date=January 2007|pmid=17161604 |doi=10.1016/j.tibs.2006.11.006 }}</ref> that aid in the [[electron transport chain]]'s ability to produce a proton gradient across the inner mitochondrial membrane.<ref>{{cite book |author =Murray, Robert F. |title=Harper's illustrated biochemistry |publisher=McGraw-Hill |location=New York |year=2003 |isbn=0-07-121766-5 }}</ref> The ATP synthase complex exists within the mitochondrial membrane (F<sub>O</sub> portion) and protrudes into the matrix (F<sub>1</sub> portion).  The energy derived as a result of the chemical gradient is then used to synthesize ATP by coupling the reaction of inorganic phosphate to ADP in the active site of the [[ATP synthase]] enzyme; the equation for this can be written as ADP + P<sub>i</sub> → ATP.{{cn|date=April 2023}}

==Blood platelet activation==
Under normal conditions, small disk-shape [[platelet]]s circulate in the blood freely and without interaction with one another. ADP is stored in [[Platelet|dense bodies]] inside [[blood]] [[platelet]]s and is released upon platelet activation. ADP interacts with a family of ADP receptors found on platelets (P2Y1, [[P2Y12]], and P2X1), which leads to platelet activation.<ref>{{cite journal |vauthors =Murugappa S, Kunapuli SP |title=The role of ADP receptors in platelet function |journal=Front. Biosci. |volume=11 |pages=1977–86 |year=2006 |pmid=16368572|url=http://www.bioscience.org/2006/v11/af/1939/fulltext.htm |doi=10.2741/1939|doi-access=free }}</ref>
* '''P2Y1''' receptors initiate platelet aggregation and shape change as a result of interactions with ADP.
* '''P2Y12''' receptors further amplify the response to ADP and draw forth the completion of aggregation.
ADP in the blood is converted to [[adenosine]] by the action of [[ecto-ADPase]]s, inhibiting further platelet activation via [[adenosine receptor]]s.{{cn|date=April 2023}}

== See also ==
* [[Nucleoside]]
* [[Nucleotide]]
* [[DNA]]
* [[RNA]]
* [[Oligonucleotide]]
* [[Apyrase]]
* [[Phosphate]]
* [[Adenosine diphosphate ribose]]

==References==
{{Reflist|2}}

{{Nucleobases, nucleosides, and nucleotides}}
{{Neurotransmitters}}
{{Purinergics}}
{{Authority control}}

{{DEFAULTSORT:Adenosine phosphate2}}
[[Category:Adenosine receptor agonists]]
[[Category:Neurotransmitters]]
[[Category:Nucleotides]]
[[Category:Cellular respiration]]
[[Category:Purines]]
[[Category:Purinergic signalling]]
[[Category:Pyrophosphate esters]]