Noun
avidin (countable and uncountable, plural avidins)
(biology) A tetrameric protein produced in the oviducts of birds, reptiles and amphibians and deposited in the whites of their eggs.
Because both streptavidin and avidin bind biotin with high affinity (K d of 10 −14 mol/l to 10 −15 mol/l) and specificity, biotinylated proteins of interest can be isolated from a sample by exploiting this highly stable interaction. Source: Internet
To circumvent this problem, beads conjugated to monomeric avidin can be used, which has a decreased biotin-binding affinity of ~10 −8 mol/l, allowing the biotinylated protein of interest to be eluted with excess free biotin. Source: Internet