View source for Iso-electric focussing

Iso-electric focussing ('''IEF''')&nbsp;is a molecular separation technique, often used to separate proteins.&nbsp; 

'''IEF''' works on the basic principle of a [[proteins|proteins]] [[isoelectric point|isoelectric point]] ('''pI'''). This is the pH at which a protein&nbsp;has an overall charge of zero.<br> 

== Procedure  ==

Firstly a gel is established with a '''pH''' gradient. This is acheived by the [[electrophoresis|electrophoresis]] of a mixture of [[polyampholytes|polyampholytes]] (small multi-charged polymers). 

You then add the sample in the middle of the gel and apply a voltage. This will involve a cathode at one end and an anode at the opposite end of the gel. 

The proteins will then start to move according to their charge.&nbsp;Positively charged proteins will move towards the [[cathode|cathode]], and&nbsp;negatively charged proteins will move towards the [[anode|anode]]. Once the proteins reach a point on the gel where the '''pH&nbsp;= pI''', the protein will stop moving. 

This separation technique is so precise, it can separate proteins with as little as one net charge differences <ref>Berg J., Tymoczko J., Stryer L., (2012) Biochemistry, 7th Edition, New York: W. H. Freeman and Company. pg 75. </ref> 

== Uses  ==

When the proteins reach their '''pI''', they form bands, these can be removed and used in further experiments.<br> 

== References  ==

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