Editing Chromatography (section)

=== Affinity chromatography ===
{{further|Affinity chromatography}}
Affinity chromatography<ref>{{cite book |title=Affinity Chromatography |vauthors=Wilchek M, Chaiken I |publisher=Humana Press |year=2000 |isbn=978-1-60327-261-2 |veditors=Bailon P, Ehrlich GK, Fung WJ, Berthold W |series=Methods in Molecular Biology |volume=147 |pages=1–6 |chapter=An Overview of Affinity Chromatography |doi=10.1007/978-1-60327-261-2_1 |pmid=10857080}}</ref> is based on selective non-covalent interaction between an analyte and specific molecules. It is very specific, but not very robust.<ref>{{cite book |last1=Urh |first1=Marjeta |title=Guide to Protein Purification, 2nd Edition |last2=Simpson |first2=Dan |last3=Zhao |first3=Kate |year=2009 |isbn=9780123745361 |series=Methods in Enzymology |volume=463 |pages=417–438 |chapter=Chapter 26 Affinity Chromatography |doi=10.1016/S0076-6879(09)63026-3 |pmid=19892186 |chapter-url=https://pubmed.ncbi.nlm.nih.gov/19892186/}}</ref> It is often used in biochemistry in the purification of [[protein]]s bound to tags. These [[fusion protein]]s are labeled with compounds such as [[His-tag]]s, [[biotin]] or [[antigen]]s, which bind to the stationary phase specifically. After purification, these tags are usually removed and the pure protein is obtained.

Affinity chromatography often utilizes a biomolecule's affinity for the [[cations]] of a metal (Zn, Cu, Fe, etc.).  Columns are often manually prepared and could be designed specifically for the proteins of interest. Traditional affinity columns are used as a preparative step to flush out unwanted biomolecules, or as a primary step in analyzing a protein with unknown physical properties.<ref>{{cite journal |last=Markwell |first=John |date=September 2009 |title=Fundamental laboratory approaches for biochemistry and biotechnology, 2nd edition |journal=Biochemistry and Molecular Biology Education |volume=37 |issue=5 |pages=317–318 |doi=10.1002/bmb.20321 |issn=1470-8175 |doi-access=free}}</ref>

However, liquid chromatography techniques exist that do utilize affinity chromatography properties.  Immobilized metal affinity chromatography (IMAC)<ref>{{cite book |title=Affinity Chromatography |vauthors=Singh NK, DSouza RN, Bibi NS, Fernández-Lahore M |year=2015 |isbn=978-1-4939-2447-9 |veditors=Reichelt S |series=Methods in Molecular Biology |volume=1286 |pages=201–12 |chapter=Direct Capture of His6-Tagged Proteins Using Megaporous Cryogels Developed for Metal-Ion Affinity Chromatography |doi=10.1007/978-1-4939-2447-9_16 |pmid=25749956}}</ref><ref>{{cite journal |vauthors=Gaberc-Porekar V, Menart V |date=October 2001 |title=Perspectives of immobilized-metal affinity chromatography |journal=Journal of Biochemical and Biophysical Methods |volume=49 |issue=1–3 |pages=335–60 |doi=10.1016/S0165-022X(01)00207-X |pmid=11694288}}</ref> is useful to separate the aforementioned molecules based on the relative affinity for the metal.  Often these columns can be loaded with different metals to create a column with a targeted affinity.<ref>{{cite journal |last1=Mahmoudi Gomari |first1=Mohammad |last2=Saraygord-Afshari |first2=Neda |last3=Farsimadan |first3=Marziye |last4=Rostami |first4=Neda |last5=Aghamiri |first5=Shahin |last6=Farajollahi |first6=Mohammad M. |date=December 2020 |title=Opportunities and challenges of the tag-assisted protein purification techniques: Applications in the pharmaceutical industry |url=https://www.sciencedirect.com/science/article/abs/pii/S0734975020301555 |journal=Biotechnology Advances |language=en |volume=45 |pages=107653 |doi=10.1016/j.biotechadv.2020.107653 |issn=0734-9750 |pmid=33157154 |s2cid=226276355}}</ref>