Peptide segment ligation: A new method for synthesis of peptide and protein

The protein structure-function relationships are always highlighted in the field of life science. Protein synthesis from genomic sequence data is gaining significance in the “post-genomic era” of biomedical research by providing direct access to functional proteins. The manually or automatically stepwise solid phase peptide synthesis (SPPS) allows peptide of up to 60 residues to be routinely constructed in good yield and high purity^1,2]. The assembly of longer proteins via the gene engineering technology (e.g. recombinant DNA-based molecular biology or site-directed mutagenesis) and convergent peptide synthesis are necessary. Although the current biosynthetic method allows unnatural amino acids to be incorporated into proteins or peptides^3], only a-peptide in the protein backbone can be obtained. A lot of problems associated with the classic convergent peptide synthesis approach, such as the poor solubility, inadequate purification techniques, and limited characterization methods with the fully protected segment^6]. However, totally chemical synthetic method can easily obtain b- or g-peptide^4] and even branch peptide^5].