Gel Filtration Media
Gel filtration chromatography is mainly based on the size and shape of the protein for separation and purification. The packing materials in the chromatography column are some inert porous network structure substances, mostly cross-linked glycans (such as dextran or agarose) so that protein mixtures could be separated according to different molecular sizes.
Ion Exchange Media
The separation of proteins by ion exchange chromatography can be achieved according to the different charges of proteins under a certain pH condition. Due to most biological molecules have acidic or alkaline groups, anion exchange media can bind with the negatively charged proteins whilst cation exchange media can bind with the positively charged proteins. By adjusting the pH of buffer, proteins with poor binding capacity will be eluted first, and proteins with strong binding capacity be eluted later.
Hydrophobic chromatography is a method to separate biological macromolecules according to their surface hydrophobicity. Some hydrophobic groups are often exposed to the surface of biological macromolecules (such as proteins and peptides). Hydrophobic groups can bind with hydrophobic chromatography media by hydrophobic interaction. Due to the different hydrophobicity of various molecules, the hydrophobic effect between molecules and media is different. Hydrophobic chromatography separates and purifies biological macromolecules according to this principle.
Affinity chromatography is a method to separate biomacromolecule based on the characteristics of specific recognition and reversible binding between biomacromolecule and some corresponding specific molecules. Affinity chromatography is an very effective method to separate proteins and usually proteins with high purity can be obtained by one-step treatment. Proteins can be separated according to their specificity to specific ligands rather than their ability to covalently bind.