Affitin Library Construction

Creative Biolabs offers custom scaffold library construction service for affitin (also known as Sac7d variants). Our scientists have developed a powerful platform, Hi-Affi™, for generation of scaffold libraries with 100% precise mutantation and over 1010 diversity.

Affitins, variants of the unique scaffold protein of Sac7d, are artificial binding proteins with extremely high affinity (up to 140 pM). Sac7d is a small (66 amino acids), highly stable DNA-binding protein from the hyperthermophilic archaeon Sulfolobus acidocaldarius. It has a well characterized heat, pH and chemically stable SH3-like five-stranded β-barrel capped by an α-helix. Furthermore, Sac7d is devoid of disulphide bridges. Proteins with this structural motif specifically recognize a wide range of substrates such as oligosaccharides, oligonucleotides, proteins, and metal ions. Specificity is mediated by variations of specific amino acid residues located at conserved positions on the binding face.

Affitin was previously selected by ribosome display from a combinatorial library prepared by randomizing 14 residues located in the original DNA binding face of Sac7d. With their small size and their low structural complexity, affitins occupy an intermediate position between peptides and proteins. They can bind different binders via two different modes of binding: one involving a flat surface and the other involving a flat surface and two short loops. The phage display affitin libraries have been used to select specific binders that may inhibit different glycosidase.

Our affitin libraries are designed so as to fully redirect the molecular recognition against any target presented which resulting in a large collection of affitin that binds specifically to the target with high affinity. Such affitin combines both a specific, high affinity binding on the target and conservation of the original stability features, i.e. being thermophilic and acidophilic. Moreover, the use of affitin offers valuable tools for probing protein structure in vivo and in vitro.

Using our proprietary Hi-Affi™ phage display technology, we generate affitin libraries with desired diversity. Devised to expand the diversity of affitin libraries, we have developed trimer codon mutant library construction technology, which offers 100% precise mutant library construction with the expected size of over 1010.

Features of our Hi-Affi™ platform:

Creative Biolabs has rich experience in the field of scaffold library construction, such as EETI-II, intrabody, avimer and so on. Our scientists are confident in offering the best service to accelerate customers’ research project with high efficiency and reasonable price.

Affitin Library Construction Fig. 1 Schematic representation of affitin libraries. (Correa et al. 2014)


  1. Correa, A., Pacheco, S., Mechaly, A. E., Obal, G., Béhar, G., Mouratou, B., Oppezzo, P., Alzari, P. M. and Pecorari, F. (2014) 'Potent and specific inhibition of glycosidases by small artificial binding proteins (Affitins)', PLoS One, 9(5), e97438.

All listed customized services & products are for research use only, not intended for pharmaceutical, diagnostic, therapeutic or any in vivo human use.

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