Study On Organic Synthesis Of Bioactive Polypeptides Based On Non-Natural Amino Acid Molecules

Bioactive ploypeptide are involved in almost all physiological activities(reproduction,genetics,development,etc.)in living organisms and are attracted widely attention from researchers.Because bioactive peptides have good biological activity,high target selectivity,and excellent metabolic stability,they are widely considered by pharmaceutical companies and scientific researchers as a very promising therapeutic molecule for disease diagnosis.The researchers found that most of the biologically active peptides(such as oxytocin,hepcidin,insulin.)mainly stabilize the secondary structure through disulfide bonds,and the proper pairing of disulfide bonds plays an important role in the maintenance of their spatial structure.However,natural disulfide bonds are easily broken by the reductive environment,which in turn destroys the steric structure of biologically active peptides,leading to their loss of biological activity.The development of alternative disulfide bonds has important implications for stabilizing the secondary structure of biologically active peptides.The reported diamino acid strategy for disulfide replacement is an efficient and practical method.However,there are disadvantages such as the presence of protective groups in diamino diacids that are not orthogonal and require the use of metal reagents.In order to solve the above problems,we have developed a truly orthogonal new type of protective group Tbe/Mtt.Based on the protective group Tbe/Mtt,we synthesized a novel diaminodioic acid and successfully prepared the polypeptide drugs oxytocin and hepcidin.On the other hand,ubiquitin is involved in many processes of cells as an important bioactive peptide in vivo,including protein degradation,cellular immune response,DNA repair.In order to elucidate the molecular mechanism of polyubiquitin chain regulation,we need to obtain sufficient and Homogenous polyubiquitin chains.However,how to construct isopeptide bonds is a major bottleneck for the study of ubiquitinated proteins.We constructed a prosthetic group on the expressed ubiquitin protein,and successfully obtained the K48-linked diubiquitin mimetic by using a hydrazide-based prosthetic group-mediated natural chemical ligation strategy,and proved by mass spectrometry experiments that the chemical synthesis of the bi-ubiquitin The theoretical molecular weight of the hormone is consistent with the actual molecular weight.In addition,we constructed K48-linked,K6-linked triubiquitin and K6,48-linked hybrid chains using two natural chemical linkages by constructing bifunctional groups containing both hydrazide and prosthetic groups on the same molecule.Type of tri-ubiquitin.Circular dichroism spectra demonstrated that our synthesized polyubiquitin chains have the correct secondary structure.Also,deubiquitinase hydrolysis experiments demonstrated that polyubiquitin chains have biological activity.