Peptides, as active substances regulating various cell functions in vivo, have become an important direction of new drug research because of their certain advantages over small molecule chemical drugs However, due to poor stability and other reasons, its application is greatly limited. Through structural modification of peptides, their physical and chemical properties can be improved, and then their stability can be improved, so that they have higher biological activity The modified peptide has better lipid - water partition coefficient and is easy to be absorbed through membrane Studies have shown that the modified peptide can significantly reduce the toxic and side effects of the drug, prolong the half-life and improve the efficacy of the drug

Peptide modification includes: phosphorylation, which is a post-translational modification(from custom peptide synthesis). The common phosphorylation targets are serine, threonine and tyrosine; Glycosylation is involved in biological development, metabolism and other important life processes, such as protein ng glycosylation modification; Cyclization, the cyclization of polypeptides is divided into head to tail connection, side chain to terminal connection, side chain to side chain connection. The side chain is generally connected through disulfide bridge, which is a common method to improve the stability of polypeptides