Affibody molecule
Affibody molecules are small, robust
Development
As with other antibody mimetics, the idea behind developing the Affibody molecule was to apply a combinatorial protein engineering approach on a small and robust protein scaffold. The aim was to generate new binders capable of specific binding to different target proteins with almost good affinity, while retaining the favorable folding and stability properties, and ease of bacterial expression of the parent molecule.[4][5]
The original Affibody protein scaffold was designed based on the Z domain (the immunoglobulin G binding domain) of protein A. These molecules are the newly developed class of scaffold proteins derived from the randomization of 13 amino acids located in two alpha helices involved in the binding activity of the parent protein domain. Lately, amino acids outside of the binding surface have been substituted in the scaffold to create a surface entirely different from the ancestral protein A domain.
In contrast to antibodies, Affibody molecules are composed of alpha helices and lack disulfide bridges. The parent three-helix bundle structure is currently the fastest folding protein structure known.[6] Specific Affibody molecules binding a desired target protein can be “fished out” from pools (libraries) containing billions of different variants, using phage display.
Production
Affibody molecules are based on a three-helix bundle domain, which can be expressed in soluble and
They tolerate modification and are independently folding when incorporated into fusion proteins. Head-to-tail fusions of Affibody molecules of the same specificity have proven to give avidity effects in target binding, and head-to-tail fusion of Affibody molecules of different specificities makes it possible to get bi- or multi-specific affinity proteins. Fusions with other proteins can also be created genetically[8][9] or by spontaneous isopeptide bond formation.[10] A site for site-specific conjugation is facilitated by introduction of a single cysteine at a desired position, therefore this engineered protein can be used to conjugate to radionuclides such as technetium-99m and indium-111 to visualize receptor-overexpressing tumors.[11][12]
A number of different Affibody molecules have been produced by
Properties
An Affibody molecule consists of three alpha helices with 58 amino acids and has a
Affibody molecules have been shown to withstand high temperatures (90 °C (194 °F)) or acidic and alkaline conditions (pH 2.5 or pH 11, respectively).[16][17][18]
Binders with an affinity of down to sub-nanomolar have been obtained from native library selections, and binders with
Applications
Affibody molecules can be used for
References
- PMID 28336959.
- PMID 26847636– via SPANDIDOS PUBLICATIONS.
- PMID 24665085.
- PMID 8532685.
- S2CID 25252394.
- PMID 15044721.
- PMID 9097850.
- PMID 11861078.
- PMID 14580889.
- PMID 26787909.
- S2CID 7995180.
- PMID 19164241.
- ^ PMID 11488921.
- S2CID 5895074.
- ^ a b "Phusion Hot Start High-Fidelity DNA Polymerase". Finnzymes. Archived from the original on 2009-03-28.
- PMID 19372467.
- PMID 17464277.
- PMID 17944527.
- ^ PMID 16618759.
- PMID 19759009.
- Science Direct.
- S2CID 29621968.
- PMID 17203961.
- PMID 17196217.
- PMID 17363599.
- PMID 20226194.
- PMID 19501012.
- PMID 26877784.
- PMID 24665085.
- S2CID 25959793.
- PMID 27748899.