avidins

Avidins are a group of proteins found in the egg whites of birds and reptiles. They are part of the avidin-biotin complex, which plays a crucial role in various biological processes. Avidins are tetrameric proteins, each consisting of four identical subunits. They are known for their high affinity for biotin, a vitamin that is essential for cellular metabolism. The binding of biotin to avidin is extremely strong, with a dissociation constant (Kd) in the picomolar range, making it one of the strongest non-covalent interactions known in biology.

Avidins have several applications in biochemistry and molecular biology. They are often used as affinity ligands in purification techniques, such as biotinylation and streptavidin-biotin affinity chromatography. Avidins are also used in the development of biosensors and bioassays due to their high specificity and sensitivity. Additionally, avidins have been studied for their potential use in drug delivery systems and as therapeutic agents.

Avidins are classified into two main types: avidin and streptavidin. Avidin is derived from the egg white of birds, while streptavidin is derived from the bacterium Streptomyces avidinii. Streptavidin is often preferred in research due to its higher stability and resistance to denaturation compared to avidin. Both avidins and streptavidin have been extensively studied and characterized, contributing to our understanding of protein-protein interactions and their applications in various fields.