1. Affinity chromatography: a chromatographic technique that utilizes the special, reversible affinity binding between a molecule and its ligand to separate the molecules.
Principle: The affinity molecules with special structure are made into solid-phase adsorbents placed in the chromatography column, when the protein mixture to be separated through the column, the proteins that have affinity with the adsorbent will be adsorbed and retained in the column. Those proteins which have no affinity for the adsorbent will be adsorbed and retained in the chromatographic column. Those proteins which have no affinity for the adsorbent will not be adsorbed and will flow out directly, thus separating from the separated proteins, and the appropriate eluent will be used to change the binding conditions to elute the bound proteins.
2. Gel filtration: the use of a certain size of pores with a network structure of the gel as a chromatographic medium (such as dextran gel, agarose gel, polyacrylamide gel, etc.), according to the molecular size of the substances to be separated, the shape of the different diffusion rate into the pores of the gel different speeds, and thus through the column of the different speeds of the separation of a kind of chromatographic method.
Principle: Gel filtration chromatography (gel filtration chromatography) method, also known as barrier chromatography or molecular sieve method, is mainly based on the size and shape of the protein, i.e., the quality of the protein for separation and purification. The packing material in the chromatography column is some inert porous mesh structure material, mostly cross-linked polysaccharide (such as dextran or agarose) type material, so that the substances in the protein mixture are separated according to the difference in molecular size. Also called molecular-exclusion chromatography. A chromatographic technique in which proteins or other molecular mixtures are separated according to molecular size using perforated gel beads as a substrate. Generally, large molecules flow out first and small molecules flow out later.
3. Polyacrylamide gel electrophoresis: used to separate proteins and oligonucleotides.
Principle of action Polyacrylamide gel electrophoresis is a mesh structure, with molecular sieve effect. It has two forms: (1) non-denaturing polyacrylamide gel, in the process of electrophoresis, the proteins can maintain the intact state, and according to the molecular weight of the protein size, the shape of the protein and the amount of charge attached to it, and the gradient of separation.
4. Salt precipitation: the phenomenon of increasing the concentration of neutral salt to reduce the solubility of proteins, gases, and uncharged molecules. Protein separation and purification is often used in the method, the most commonly used neutral salts are ammonium sulfate, sodium sulfate and sodium chloride.