What are proteins?
Proteins are the main building blocks of life. They are essential for the body and have many different roles . Proteins are made from sequence of amino acids. Protein structure is determined by their sequence of amino acids, which are linked by peptide link. Proteins are made from about 50 to 2000 amino acid residues.
Figure 1
Why purify proteins?
They are many reasons why a biochemist might want to purify a protein. For example to analyse and identify the protein and see the function of the protein. A protein can be analysed to study the structure of it and for ‘post-translational modifications’. This is when the protein is modified after the later stages of protein synthesis ‘translation’.
Chromatographic method
The purification of proteins requires several tehcniques and which technique to use is depedendant on what protein is being analayzed. The properties of the protein will be taken into consideration and what tecnhique suits best. The idea is to be able to isolate the protien that is in interest from the protiens that are not needed. Below are several chromatography techniques that are used to analyze proteins.
Size exclusion chromatography (SEC)
In this type of technique the protein is separated according to the size of the protein. The matrixes used in size exclusion chromatography have a range of beads with different pore sizes (H. Dai). The seperation of the protein is dependent on how the protein can enter the channels of the porous. Proteins that are small in size are more likely to fit in one of the channels than the larger proteins, so the larger proteins flow quickly through the beads and the smaller molecules will flow through slowly.
The Stationary Phase
The matrix used for the stationary phase in the SEC is chosen so that there is minimal adsorption. There are many gels
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