APPI Library Construction

Creative Biolabs provides APPI phage display library construction service by our Hi-Affi™ phage display platform. The platform is specifically developed for generating high quality scaffold protein libraries.

Alzheimer’s amyloid β-protein precursor inhibitor (APPI) is one member of Kunitz family protease inhibitors. Kunitz is a family of small α/β-proteins of approximately 60 amino acids. This scaffold family comprises irregular few secondary structure elements but well stabilized by three disulfide bonds and exposes multiple variable domains. Naturally, they act in the manner of slow but tight-binding, reversible inhibitors of serine proteases.

APPI has been used as scaffold for presenting binding peptides. It was served as a scaffold for selection novel Kunitz domain inhibitors of the human tissue factor/factor VIIa (TF-FVIIa) complex, which plays an essential role at the initial phase of the blood coagulation cascade. The libraries can be constructed by mutating several positions of the APPI sequence which distributed among the extended primary binding loop and a closely neighboring loop and comprised a discontinuous paratope. Then the mutants can be displayed as pIII fusion protein on the surface of M13 phagemid to against TF-FVIIa complex. In this way, APPI can be chosen as a potential scaffold especial for the targets relate to Kunitz family.

Creative Biolabs developed the proprietary Hi-Affi™ phage display platform for scaffold protein library construction. For this platform, our scientists have adopted trimer codon technology and NNK method combined with phage display technology. Compared with traditional phage display technology, which is an exogenous gene expression method through fusing the target genes to bacteriophage coat proteins then displaying on the phage surfaces to select specific binders, Hi-Affi phage display platform is more suitable for sorting and isolating the high affinity protein or peptide targets. It can improve the library diversity by introducing more randomicity and also enhance the affinity. Ultimately, the generated APPI phage display library can achieve 100% precise mutant and over 1010 diversity.

Creative Biolabs is a long-term expertise in library construction field. Our scientists have generated more than 50 kinds of scaffold libraries with the best quality and reasonable price for our global customers. We are more than happy to tailor special scaffold protein library for our global customers and facilitate their research and project.

APPI Library Construction
Fig. 1 Human mesotrypsin complexed with amyloid precursor protein inhibitor (APPI). (PDB ID: 3L33)

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