Editing Adenosine triphosphate (section)

==Structure==
ATP consists of three parts: a sugar, an amine base, and a phosphate group.<ref name="Myers" /> More specifically, ATP consists of an [[adenine]] attached by the #9-nitrogen atom to the 1′ [[carbon]] [[atom]] of a sugar ([[ribose]]), which in turn is attached at the 5' carbon atom of the sugar to a triphosphate group. In its many reactions related to metabolism, the adenine and sugar groups remain unchanged, but the triphosphate is converted to di- and monophosphate, giving respectively the derivatives [[adenosine diphosphate|ADP]] and [[adenosine monophosphate|AMP]]. The three phosphoryl groups are labeled as alpha (α), beta (β), and, for the terminal phosphate, gamma (γ).<ref>{{Citation |last1=Dunn |first1=Jacob |title=Physiology, Adenosine Triphosphate |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK553175/ |work=StatPearls |access-date=2023-09-28 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31985968 |last2=Grider |first2=Michael H.}}</ref>

In neutral solution, ionized ATP exists mostly as ATP<sup>4−</sup>, with a small proportion of ATP<sup>3−</sup>.<ref name=Storer>{{cite journal |last1=Storer |first1=A.|author-link2=Athel Cornish-Bowden |last2=Cornish-Bowden |first2=A. | title = Concentration of MgATP<sup>2−</sup> and other ions in solution. Calculation of the true concentrations of species present in mixtures of associating ions | pmc=1164030 | journal = Biochem. J. | volume = 159 | issue = 1 | pages = 1–5 | year = 1976 | pmid = 11772 | doi=10.1042/bj1590001}}</ref>

===Metal cation binding===
Polyanionic and featuring a potentially [[chelation|chelating]] polyphosphate group, ATP binds metal cations with high affinity. The [[binding constant]] for {{chem|link=magnesium|Mg|2+}} is ({{gaps|9|554}}).<ref>{{cite journal |last1=Wilson |first1=J. |last2=Chin |first2=A. | title = Chelation of divalent cations by ATP, studied by titration calorimetry | journal = Anal. Biochem. | volume = 193 | issue = 1 | pages = 16–19 | year = 1991 | pmid = 1645933| doi=10.1016/0003-2697(91)90036-S}}</ref>  The binding of a [[divalent]] [[cation]], almost always [[magnesium]], strongly affects the interaction of ATP with various proteins. Due to the strength of the ATP-Mg<sup>2+</sup> interaction, ATP exists in the cell mostly as a complex with {{chem|Mg|2+}} bonded to the phosphate oxygen centers.<ref name=Storer/><ref>{{cite journal |last1=Garfinkel |first1=L. |last2=Altschuld |first2=R. |last3=Garfinkel |first3=D. | title = Magnesium in cardiac energy metabolism | journal = J. Mol. Cell. Cardiol. | volume = 18 | issue = 10 | pages = 1003–1013 | year = 1986 | pmid = 3537318 | doi = 10.1016/S0022-2828(86)80289-9 }}</ref>

A second magnesium ion is critical for ATP binding in the kinase domain.<ref name="Saylor">{{cite journal |last1=Saylor |first1=P. |last2=Wang |first2=C. |last3=Hirai |first3=T. |last4=Adams |first4=J. | title = A second magnesium ion is critical for ATP binding in the kinase domain of the oncoprotein v-Fps | journal = Biochemistry | volume = 37 | issue = 36 | pages = 12624–12630 | year = 1998 | pmid = 9730835 | doi = 10.1021/bi9812672 }}</ref> The presence of Mg<sup>2+</sup> regulates kinase activity.<ref name=Lin>{{cite journal |last1=Lin |first1=X. |last2=Ayrapetov |first2=M |last3=Sun |first3=G. | title = Characterization of the interactions between the active site of a protein tyrosine kinase and a divalent metal activator |pmc=1316873 | doi = 10.1186/1471-2091-6-25 |doi-access=free | journal = BMC Biochem. | volume = 6 | pages = 25 | year = 2005| pmid = 16305747}}</ref>   It is interesting from an RNA world perspective that ATP can carry a Mg ion which catalyzes RNA polymerization.{{citation needed|date=December 2023}}