Native Chemical Ligation at Valine

摘要

Among the techniques employed-for coupling peptide segments,native chemical ligation is among the most useful.Since its discovery it has become a powerful tool for the chemical synthesis of proteins including labeled or posttrans-lationally modified proteins and proteins that contain non-proteinogenic amino acids.In the native chemical ligation an unprotected C-terminal peptide thioester reacts with an unprotected N-terminal cysteine residue.The requirement for the rare amino acid cysteine limits the applicability in the synthesis of naturally occurring proteins.Several approaches have been developed to allow access to other,more common ligation sites.