Discussion

Antibodies are a major tool for life scientists in any discipline, whether working in academia, agri-tech or large pharma. However, antibodies cannot always be generated to a given target, and cannot always be relied upon to bind the right target. A number of groups have sought to develop alternative, non-antibody binding reagents, with varying degrees of success. Here, we describe Affimers as a next-generation non-antibody affinity reagent.
The Affimer protein scaffold (represented symbolically as Ψ) is a biologically inert, biophysically stable scaffold derived from the cystatin family of protease inhibitors. The scaffold is capable of presenting a range of designed or random binding surfaces (defined by peptides inserted at loop 1, loop 2 and the amino terminus) for highly specific, high affinity interactions with a wide range of targets. Affimers have been shown to perform as well as the very best antibodies in a range of standard assays (e.g. enzyme linked sorbent assays, Westerns, SPR, affinity-pull downs). Large phage (10^10) and CIS display (10^13) Affimer libraries are now available and and Avacta Life Sciences now offers a 7 week screening and characterisation program to deliver Affimers that recognise virtually any biological molecule of interest.