Creative Biolabs has extensive experience to offer the best service for the aptide library construction. Based on our advanced phage display platform, our scientists now can proudly provide unique aptide library construction service with high quality, affinity, and the abundant diversity of over 1010.
Aptide, which is termed by Kim et al. (2012), is an artificial aptamer-like peptide ligand. It can mimic the DNA recognition site of basic leucine zipper (bZIP) proteins to work as a transcriptional regulator with sequence-specific and high-affinity recognition of unique DNA motifs in all eukaryotes. The structure analysis has shown single aptide comprises a stabilizing scaffold and two target-binding regions. The scaffold consists of a small (12 amino acids) but highly stable tryptophan zipper that forms a leucine-zipper-like β-hairpin structure, in which two tryptophan-tryptophan cross-strand pairs create a robust and stable structure. As for the two target-binding regions, there are six randomized amino acids in each end of the trpzip scaffold through glycine linkers, which enable aptides to bind their targets with high affinity and specificity, just like the mimicked DNA recognition site of bZIP proteins. These two random regions enable the library construction. Meanwhile, we can also add a 9R sequence at the C-terminal of target-binding regions to improve its cell-penetrating ability.
The special structure of aptide makes it available to be developed as phage display libraries for screening against protein targets. As a general source of high-affinity binding molecules, aptide libraries have been screened for several typical targets, such as VEGF, CD7 and a validated tumor-specific biomarker: human fibronectin extra domain B (EDB). According to the report of Kim et al. (2012), specific aptide binders have been isolated for these targets with relatively higher affinity than other previous binding molecules. For instance, the selected VEGF-specific aptide shows an affinity of approximately 30 nm, which is the highest affinity of any reported VEGF-binding peptides (Kim et al. 2012). In addition, the EDB-specific aptide also shows the ability to bind the target in vivo. Therefore, aptides are considered as a novel class of molecules which have great potentials in biological and biomedical research and also in diagnostic and therapeutic applications.
Scientists from Creative Biolabs have built up the proprietary Hi-Affi™ phage display platform to generate scaffold libraries for sorting and isolating the high-affinity protein or peptide targets. For phage display based selections, the aptide libraries are adapted for monovalent display on filamentous bacteriophage surfaces for further selection and isolation. To create a high-quality aptide library, the main step is to synthesize two degenerate aptide-encoding oligonucleotides so that create double-stranded randomized inserts. During the construction, a high diversity can be achieved through introducing mutation sites by timer codon technology, error-prone PCR or NNK method. As a result, we are able to obtain 100% precisely mutated library with over 1010 diversity.
Creative Biolabs is a long-term expert in the field of scaffold library construction. We have generated about 55 kinds of scaffold libraries for clients all over the world by now. Our scientists are confident in constructing aptide libraries for customers with higher efficiency, better quality, and reasonable price. If you are interested in our aptide library construction service, please do not hesitate to inquire us for more details.
Fig. 1 a) Design rationale of an aptide. b) NMR structures of an aptide. (Kim et al. 2012)