Design and Construction of a Selection Peptide Library Based on the Human Thymic Hormone Thymopoietin Domain

摘要

The activity sites of thymic hormone thymopoietin (TPN) [1] have different biological functions depending on different amino acid sequences, providing a new scaffold for designing peptide inhibitors. In this study, we constructed TPN-based peptide library displayed on the surface of Escherichia coli strain using FimH fusion protein [2]. In principle, the activity site residues of TPN were substituted with randomized peptide sequences and each bacterial cell displayed multiple copies of the same peptide. We checked the bacterial expression on surface of E. coli and the feasibility of the peptide library using a histidines-tag and SDS-PAGE analysis. The histidineg fusion scaffold protein visualized by scanning transmission electron microscopy (STEM) with Ni-NTA-modified magnetic nanoparticles demonstrates that a large fraction of our library expresses to be membrane protein. Furthermore, we proved that the library expressed on the surface of E. coli with SDS-PAGE analysis of expression cultures show a large ratio of protein to be insoluble. As expected, the TPN-peptide library was also confirmed to contain 3 x 10~4 peptides of random 7-amino acid sequences. The results indicate that many kinds of peptide sequences containing in the TPN scaffold is an efficient technique for screening of peptide drugs.