Chromatography

2017-10-23T19:18:48Z

170627160:

In order to study [[Proteins|proteins]] individually, they need to be separated from each other. This can be done due to the fact that they have different sizes, shapes, [[Hydrophobic|hydrophobicity]] and have different [[Affinity chromatography|affinities]] for other molecules.<ref>Alberts, B (2004). Essential Cell Biology. 2nd ed. New York: Garland Science. 162</ref> 

Examples of common chromatography methods include: [[Ion exchange chromatography|ion exchange chromatography]], [[Size exclusion chromatography|size exclusion chromatography]], [[Affinity binding chromatography|affinity binding chromatography]] and [[Hydrophobic interaction chromatography|hydrophobic interaction chromatography]].

[[Ion exchange chromatography|Ion exchange chromatography]] separates molecules according to their overall charge. Positively charged molecules stick to the column whereas negatively charged molecules are eluted first with the [[Buffer|buffer]]. Salt can be added to the column to elute the positively charged molecules afterwards. This process as a whole is called eluting.

Affinity chromatography takes advantage of the high affinity of many proteins for specific chemical groups. Affinity chromatography is more powerful than ion exchange chromatography by means of purifying proteins. Adding free binding partner elutes the protein[1].

The matrix for column chromatography varies although the material is normally packed in the column in the form of small porous beads. [[Gel-filtration chromatography|Gel filtration]] columns separate [[Proteins|proteins]] according to their size. Molecules small enough to enter holes in the beads are delayed and travel more slowly through the column, and those that are too large to enter the beads are washed out of the column first. These columns also allow an estimate of protein size.<ref>Alberts, B (2004). Essential Cell Biology. 2nd ed. New York: Garland Science. 162</ref>

Types of chromatography include: [[Two-dimensional chromatography|two-dimensional chromatography]], [[Thin layer chromatography|thin layer chromatography]] (TLC) and [[Paper chromatography|paper chromatography]]. [[High-performance_liquid_chromatography|High-performance liquid chromatography]] (HPLC)  and [[gas_chromatography|gas chromatography]] (GC) also types of chromatography. They are mainly used to separate and identify drugs in pharmacy. It is possible to analyze the substances quantitative just like qualitative. 

Without chromatography, and the work of [[Banting|Banting]], [[Best|Best]] and a biochemist called [[Collip|Collip]] (who perfected the purification), we would have no treatment for [[Diabetes|type I diabetes]], that is, [[Insulin|insulin]] would not have been discovered. Without chromatography we wouldn’t be able to sequence [[DNA|DNA]], perform [[PCR|PCR]], and many drugs and biological mechanisms would not have been discovered<ref>Berg, J., M., Tymoczko, J., L., Stryer, L., 2012. 7th ed. Basinstoke, England: W.H. Freeman Palgrave Macmillian</ref>. 

=== References ===

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Chromatography