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Purification of Protein by Ion-Exchange Chromatography (IEX) (CAT#: STEM-CT-3139-CJ)

Introduction

The net surface charge of a protein changes with the pH. It takes the isoelectric point (pI) of this protein as the criterion. Net surface charge of a protein is zero at the pH equals to its pI. A protein carries positive net surface charge at the pH below its own pI, and it will carry negative net surface charge if the pH is raised above its pI. Researchers must choose the right method to perform protein IEX according to the net surface charge condition of the target protein at the experimental pH.




Principle

Ion-Exchange Chromatography (IEX) is used in the separation of charged biomolecules. The crude sample containing charged molecules is used as the liquid phase. When it passes through the chromatographic column, molecules bind to oppositely charged sites in the stationary phase. The molecules separated on the basis of their charge are eluted using a solution of varying ionic strength. By passing such a solution through the column, highly selective separation of molecules according to their different charges takes place.

Applications

Biochemistry; Biopharmaceuticals; Biomedical

Procedure

Ion exchange separations are carried out mainly in columns packed with an ion-exchanger. The ionic exchangers are commercially available. They are made up of styrene and divinyl benzene. The choice of the exchanger depends upon the charge of particle to be separated. To separate anions "Anionic exchanger" is used, to separate cations "Cationic exchanger" is used.
1. First the column is filled with ion exchanger then the sample is applied followed by the buffer. The tris-buffer, pyridine buffer, acetate buffer, citrate and phosphate buffers are widely used.
2. The particles which have high affinity for ion exchanger will come down the column along with buffers. In next step using corresponding buffer separates the tightly bound particles.
3. Then these particles are analyzed spectroscopically.

Materials

• Sample: Urine; Bodily fluids; Blood; Saliva; Serum; Plasma; Drugs; Charged Biological Molecules (Such As Proteins; Peptides; Amino Acids; Nucleotides); Environmental pollutants; Water; Food & More
• Equipment: Ion Chromatography System

Notes

1. It is one of the most efficient methods for the separation of charged particles.
2. It can be used for almost any kind of charged molecule including large proteins, small nucleotides and amino acids.
3. Inorganic ions also can be separated by ion-exchange chromatography.
4. Ion Chromatography can be used for both liquid and solid samples.
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