Editing Affinity chromatography (section)

==Principle==
Affinity chromatography has the advantage of specific binding interactions between the analyte of interest (normally dissolved in the [[mobile phase]]), and a binding partner or ligand (immobilized on the [[Stationary phase (chemistry)|stationary phase]]).  In a typical affinity chromatography experiment, the ligand is attached to a solid, insoluble matrix—usually a [[polymer]] such as [[agarose]] or [[polyacrylamide]]—chemically modified to introduce reactive [[functional groups]] with which the ligand can react, forming stable covalent bonds.<ref>{{Cite book |title=Affinity Chromatography: Methods and Protocols |date=2008 |publisher=Humana Press |isbn=9781588296597 |editor-last=Zachariou |editor-first=Michael |edition=2nd |location=Totowa, N.J. |pages=1–2}}</ref> The stationary phase is first loaded into a column to which the mobile phase is introduced.  Molecules that bind to the ligand will remain associated with the stationary phase.  A wash buffer is then applied to remove non-target biomolecules by disrupting their weaker interactions with the stationary phase, while the biomolecules of interest will remain bound.  Target biomolecules may then be removed by applying a so-called elution buffer, which disrupts interactions between the bound target biomolecules and the ligand.  The target molecule is thus recovered in the eluting solution.<ref name="protein">{{Cite book|title=Protein Purification|last1=Bonner |first1= Philip L.R.|date=2007|publisher=Taylor & Francis Group|isbn=9780415385114|edition=2nd|location=Totowa, N.J.}}</ref>{{page needed|date=December 2021}}

Affinity chromatography does not require the molecular weight, charge, hydrophobicity, or other physical properties of the analyte of interest to be known, although knowledge of its binding properties is useful in the design of a separation protocol.<ref name="protein" /> Types of binding interactions commonly exploited in affinity chromatography procedures are summarized in the table below.

{| class="wikitable"
|+ Typical biological interactions used in affinity chromatography<ref>{{Cite book|title=Biophysics and Molecular Biology|last=Kumar|first=Pranav|publisher=Pathfinder Publication|year=2018|isbn=978-93-80473-15-4|location=New Delhi|page=11}}</ref>
|-
! Sr. no
! Types of ligand
! Target molecule
|-
|1
|[[Substrate analog]]ue
|Enzymes
|-
|2
|[[Antibody]]
|[[Antigen]]
|-
|3
|[[Lectin]]
|[[Polysaccharide]]
|-
|4
|[[Nucleic acid]]
|[[Complementary base sequence]]
|-
|5
|[[Hormone]]
|[[hormone receptor|Receptor]]
|-
|6
|[[Avidin]]
|[[Biotin]]/Biotin-conjugated molecule
|-
|7
|[[Calmodulin]]
|Calmodulin binding partner 
|-
|8
|[[Glutathione]]
|[[Glutathione S-transferase|GST]] [[fusion protein]]
|-
|9
|[[Protein A]] or [[Protein G]]
|[[Immunoglobulin]]s
|-
|10
|[[Nickel-NTA]]
|[[polyhistidine fusion protein]]
|}