Editing Zwitterion (section)

==Theoretical studies==
[[Image:Pyridoxal-phosphate.svg|thumb|140px|pyridoxal phosphate]]
Insight to the equilibrium in solution may be gained from the results of theoretical calculations. For example, pyridoxal phosphate, a form of [[vitamin B6|vitamin B<sub>6</sub>]], in aqueous solution is predicted to have an equilibrium favoring a tautomeric form in which a proton is transferred from the phenolic -OH group to the nitrogen atom.<ref>{{cite journal |last1=Kiruba |first1=G. S. M. |last2=Ming |first2=Wah Wong |title=Tautomeric Equilibria of Pyridoxal-5′-phosphate and 3-Hydroxypyridine Derivatives: A Theoretical Study of Solvation Effects|journal=Journal of Organic Chemistry |date=2003 |volume=68 |issue=7 |pages=2874–2881 |doi=10.1021/jo0266792|pmid=12662064 }}</ref>

Because tautomers are different compounds, they sometimes have different enough structures that they can be detected independently in their mixture. This allows experimental analysis of the equilibrium.<ref>{{cite journal |title= Theoretical and Experimental Studies of the Zwitterion ⇌ Neutral Form Equilibrium of Ampholytes in Pure Solvents and Mixtures |first1= Peter I. |last1= Nagy |first2= Krisztina |last2= Takács-Novák |journal= J. Am. Chem. Soc. |year= 1997 |volume= 119 |issue= 21 |pages= 4999–5006 |doi= 10.1021/ja963512f }}</ref>