Affitin

Affitins

Scientists have been able to purify human immunoglobulin G (hIgG), bacterial PulD protein, and chicken egg lysozyme using Affitin columns with a high degree of purity.^[5] These have the ability to act as specific ligands for the proteins of interest that are needed when the fusion of proteins to polypeptide tags is impossible or carries no advantage, and thus build affinity columns as is the case in the production of biopharmaceuticals. They were immobilized on an agarose matrix and the columns had a high degree of selectivity.^[5]

In addition to this, antibodies and non-immunoglobin proteins can be purified by using affitins via affinity chromatography.^[5] Due to their small size and high solubility, they can be easily produced in large amounts using bacterial expression systems.

Properties

Affitins consist of 66 amino acids and have a

Affitins are strongly modified reagents that are extremophilic since they are found in Archae like Sac7d, which is a hyperthermostable protein. They are artificially binding proteins with high affinity, small size, and low structural complexity. They have two different modes of binding. The first requires a flat surface whereas the second mode of binding requires a flat surface and two short loops. They are thermally and chemically stable reagents and their stability can be further increased by using mutation or grafting techniques. Other methods of stabilizing them include the use of sequence elements from other proteins that belong to the same family, switching a binding surface, and thus, have longer binding capacities. This was done by grafting the binding surface of D1Sac7d onto Sso7d, which is more stable, and by introducing point mutations previously identified as stabilizing for WT Sso7d.[6]

References