Adenosine Monophosphate

Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine. It is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-.

Adenosine monophosphate

Names
IUPAC name 5′-Adenylic acid
Systematic IUPAC name [(2R,3S,4R,5R)-5-(6-Amino-9H-purin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl dihydrogen phosphate
Other names Adenosine 5'-monophosphate
Identifiers
CAS Number	61-19-8 Y
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:16027 Y
ChEMBL	ChEMBL752 Y
ChemSpider	5858 Y
DrugBank	DB00131 Y
ECHA InfoCard	100.000.455
IUPHAR/BPS	2455
KEGG	C00020 Y
MeSH	Adenosine+monophosphate
PubChem CID	6083
UNII	415SHH325A Y
CompTox Dashboard (EPA)	DTXSID5022560
InChI InChI=1S/C10H14N5O7P/c11-8-5-9(13-2-12-8)15(3-14-5)10-7(17)6(16)4(22-10)1-21-23(18,19)20/h2-4,6-7,10,16-17H,1H2,(H2,11,12,13)(H2,18,19,20)/t4-,6-,7-,10-/m1/s1 Y Key: UDMBCSSLTHHNCD-KQYNXXCUSA-N Y InChI=1/C10H14N5O7P/c11-8-5-9(13-2-12-8)15(3-14-5)10-7(17)6(16)4(22-10)1-21-23(18,19)20/h2-4,6-7,10,16-17H,1H2,(H2,11,12,13)(H2,18,19,20)/t4-,6-,7-,10-/m1/s1 Key: UDMBCSSLTHHNCD-KQYNXXCUBP
SMILES O=P(O)(O)OC[C@H]3O[C@@H](n2cnc1c(ncnc12)N)[C@H](O)[C@@H]3O c1nc(c2c(n1)n(cn2)[C@H]3[C@@H]([C@@H]([C@H](O3)COP(=O)(O)O)O)O)N
Properties
Chemical formula	C10H14N5O7P
Molar mass	347.22 g/mol
Appearance	white crystalline powder
Density	2.32 g/mL
Melting point	178 to 185 °C (352 to 365 °F; 451 to 458 K)
Boiling point	798.5 °C (1,469.3 °F; 1,071.7 K)
Acidity (pKa)	0.9[citation needed], 3.8, 6.1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

AMP plays an important role in many cellular metabolic processes, being interconverted to adenosine triphosphate (ATP) and adenosine diphosphate (ADP), as well as allosterically activating enzymes such as myophosphorylase-b. AMP is also a component in the synthesis of RNA. AMP is present in all known forms of life.

AMP does not have the high energy phosphoanhydride bond associated with ADP and ATP. AMP can be produced from ADP by the myokinase (adenylate kinase) reaction when the ATP reservoir in the cell is low:

2 ADP → ATP + AMP

Or AMP may be produced by the hydrolysis of one high energy phosphate bond of ADP:

ADP + H₂O → AMP + P_i

AMP can also be formed by hydrolysis of ATP into AMP and pyrophosphate:

ATP + H₂O → AMP + PP_i

When RNA is broken down by living systems, nucleoside monophosphates, including adenosine monophosphate, are formed.

AMP can be regenerated to ATP as follows:

AMP + ATP → 2 ADP (adenylate kinase in the opposite direction)
ADP + P_i → ATP (this step is most often performed in aerobes by the ATP synthase during oxidative phosphorylation)

AMP can be converted into inosine monophosphate by the enzyme myoadenylate deaminase, freeing an ammonia group.

In a catabolic pathway, the purine nucleotide cycle, adenosine monophosphate can be converted to uric acid, which is excreted from the body in mammals.

AMP-activated kinase regulation

The eukaryotic cell enzyme 5' adenosine monophosphate-activated protein kinase, or AMPK, utilizes AMP for homeostatic energy processes during times of high cellular energy expenditure, such as exercise. Since ATP cleavage, and corresponding phosphorylation reactions, are utilized in various processes throughout the body as a source of energy, ATP production is necessary to further create energy for those mammalian cells. AMPK, as a cellular energy sensor, is activated by decreasing levels of ATP, which is naturally accompanied by increasing levels of ADP and AMP.

Though phosphorylation appears to be the main activator for AMPK, some studies suggest that AMP is an allosteric regulator as well as a direct agonist for AMPK. Furthermore, other studies suggest that the high ratio of AMP:ATP levels in cells, rather than just AMP, activate AMPK. For example, the AMP-activated kinases of Caenorhabditis elegans and Drosophila melanogaster were found to have been activated by AMP, while yeast and plant kinases were not allosterically activated by AMP.

AMP binds to the γ-subunit of AMPK, leading to the activation of the kinase, and then eventually a cascade of other processes such as the activation of catabolic pathways and inhibition of anabolic pathways to regenerate ATP. Catabolic mechanisms, which generate ATP through the release of energy from breaking down molecules, are activated by the AMPK enzyme while anabolic mechanisms, which utilize energy from ATP to form products, are inhibited. Though the γ-subunit can bind AMP/ADP/ATP, only the binding of AMP/ADP results in a conformational shift of the enzyme protein. This variance in AMP/ADP versus ATP binding leads to a shift in the dephosphorylation state for the enzyme. The dephosphorylation of AMPK through various protein phosphatases completely inactivates catalytic function. AMP/ADP protects AMPK from being inactivated by binding to the γ-subunit and maintaining the dephosphorylation state.

AMP can also exist as a cyclic structure known as cyclic AMP (or cAMP). Within certain cells the enzyme adenylate cyclase makes cAMP from ATP, and typically this reaction is regulated by hormones such as adrenaline or glucagon. cAMP plays an important role in intracellular signaling. In skeletal muscle, cyclic AMP, triggered by adrenaline, starts a cascade (cAMP-dependent pathway) for the conversion of myophosphorylase-b into the phosphorylated form of myophoshorylase-a for glycogenolysis.

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