
Proteins are macromolecules, consisting of one or more long chains of amino acid residues linked by peptide bonds. Protein structure comprises primary, secondary, tertiary, and quaternary structure levels. Its function and shape depends upon the amino acid sequence and the sequence of bases in the genes. Protein function in an optimal condition, and denatures when exposed to extreme conditions. Change in temperature, salt concentration, and pH can also denature the protein. Protein purification is the series of processes intended to isolate a single type of protein from a complex mixture. Protein purification is done with the help of various processes such as crude extract, salting out, fractionation, and dialysis. In fractionation, protein is separated into different fractions based on the size of the charge, whereas in crude extract, protein is separated by breaking cells with the help of osmosis or homogenization. Separation of protein is based on the chemical and physical properties such as size, shape, surface-exposed hydrophobic residues, solubility, isoelectric point, and charged surface residues. Protein purification is done for genetic engineering, antibody production, sequence determination, structural determination, finding inhibitors, and detailed kinetic studies. It is also used for the extraction of purified protein for enormously precious biochemical reagents. Protein purification is done with the help of techniques such as chromatography and electrophoresis. Chromatography is a group of separation techniques, characterized by a distribution of the molecule to be separated between the stationary and mobile phases. Affinity chromatography, ion exchange chromatography, gel filtration chromatography, and high-pressure liquid chromatography are some of the types of chromatography techniques used in protein purification. In addition, electrophoresis is the technique used to separate macromolecules based on size and it applies a negative charge as protein moves towards a positive charge. Gel electrophoresis and capillary electrophoresis are some of the electrophoresis techniques used in protein purification.