Editing Phosphate (section)

===Biochemistry of phosphates===
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In [[biological system]]s, phosphorus can be found as free phosphate anions in solution ('''inorganic phosphate''') or bound to organic molecules as various [[organophosphate]]s.<ref>Jastrzab Renata, Nowak Martyna, Zabiszak Michał, Odani Akira, Kaczmarek Małgorzata T. [https://www.sciencedirect.com/science/article/pii/S0010854521000448 Significance and properties of the complex formation of phosphate and polyphosphate groups in particles present in living cells] [https://doi.org/10.1016/j.ccr.2021.213810 10.1016/j.ccr.2021.213810] ''Coordination Chemistry Reviews''
Volume 435, 15 May 2021, 213810</ref>

Inorganic phosphate is generally denoted '''P<sub>i</sub>''' and at physiological ([[Homeostasis|homeostatic]]) [[pH]] primarily consists of a mixture of {{chem2|[HPO4](2−)}} and {{chem2|[H2PO4]−}} ions. At a neutral pH, as in the [[cytosol]] (pH = 7.0), the concentrations of the orthophoshoric acid and its three anions have the ratios
<math chem display=block>\begin{align}
  \frac{[\ce{H2PO4-}]}{[\ce{H3PO4}]} &\approx 7.5 \times 10^4 \\[4pt]
  \frac{[\ce{HPO4^2-}]}{[\ce{H2PO4-}]} &\approx 0.62 \\[4pt]
  \frac{[\ce{PO4^3-}]}{[\ce{HPO4^2-}]} &\approx 2.14 \times 10^{-6}
\end{align}</math>

Thus, only the {{chem2|[H2PO4]−}} and {{chem2|[HPO4](2−)}} ions are present in significant amounts in the cytosol (62% {{chem2|[H2PO4]−}}, 38% {{chem2|[HPO4](2−)}}). In extracellular fluid (pH = 7.4), this proportion is inverted (61% {{chem2|[HPO4](2−)}}, 39% {{chem2|[H2PO4]−}}).

Inorganic phosphate can also be present as [[pyrophosphate]] anions {{chem2|[P2O7](4-)}}, which give orthophosphate by [[hydrolysis]]:
:{{chem2|[P2O7](4-) + H2O <-> 2 [HPO4](2−)}}

Organic phosphates are commonly found in the form of esters as [[nucleotide]]s (e.g. [[Adenosine monophosphate|AMP]], [[Adenosine diphosphate|ADP]], and [[Adenosine triphosphate|ATP]]) and in [[DNA]] and [[RNA]]. Free orthophosphate anions can be released by the hydrolysis of the [[phosphoanhydride]] bonds in ATP or ADP. These [[phosphorylation]] and [[dephosphorylation]] reactions are the immediate storage and source of energy for many [[metabolism|metabolic]] processes. ATP and ADP are often referred to as [[high-energy phosphate]]s, as are the [[phosphagen]]s in muscle tissue.  Similar reactions exist for the other nucleoside [[nucleoside diphosphate|diphosphates]] and [[nucleoside triphosphate|triphosphates]].