Affilin

Affilin was developed by Scil Proteins GmbH as potential new biopharmaceutical drugs, diagnostics and affinity ligands.

[4] Historically, Affilin molecules were based on gamma crystallin, a family of proteins found in the eye lens of vertebrates, including humans.

[7] The molecular mass of crystallin and ubiquitin based Affilin proteins is only one eighth or one sixteenth of an IgG antibody, respectively.

Renal clearance, another consequence of their small size, is the reason for their short plasma half-life, generally a disadvantage for potential drugs.

In an Affilin protein comprising two modified ubiquitin molecules, for example, up to 14 amino acids are exchanged,[8] resulting in 8 × 1017 combinations, but not all of these are realized in a given library.

Subsequent dimerisation or multimerisation can increase plasma half-life and, due to avidity, affinity to the target protein.

3D structure of an Affilin based on gamma-B crystallin ( PDB : 2JDG ​)
Human gamma-B crystallin, wild-type ( PDB : 2JDF ​). The beta strands making up the beta sheets are coloured blue.
Human ubiquitin, wild-type ( PDB : 1UBQ ​). The N-terminal beta strand is the second from top, pointing right; the C-terminal strand is the one in front, pointing right and downwards. The exchangeable amino acids are located at the top left.