Synthesis of peptides and proteins without cysteine residues by native chemical ligation combined with desulfurization

J Am Chem Soc. 2001 Jan 31;123(4):526-33. doi: 10.1021/ja003265m.


The highly chemoselective reaction between unprotected peptides bearing an N-terminal Cys residue and a C-terminal thioester enables the total and semi-synthesis of complex polypeptides. Here we extend the utility of this native chemical ligation approach to non-cysteine containing peptides. Since alanine is a common amino acid in proteins, ligation at this residue would be of great utility. To achieve this goal, a specific alanine residue in the parent protein is replaced with cysteine to facilitate synthesis by native chemical ligation. Following ligation, selective desulfurization of the resulting unprotected polypeptide product with H(2)/metal reagents converts the cysteine residue to alanine. This approach, which provides a general method to prepare alanyl proteins from their cysteinyl forms, can be used to chemically synthesize a variety of polypeptides, as demonstrated by the total chemical syntheses of the cyclic antibiotic microcin J25, the 56-amino acid streptococcal protein G B1 domain, and a variant of the 110-amino acid ribonuclease, barnase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aminobutyrates / chemistry
  • Bacterial Proteins / chemical synthesis
  • Bacteriocins / chemical synthesis
  • Cysteine / chemistry*
  • Methods
  • Peptides / chemical synthesis*
  • Proteins / chemical synthesis*
  • Ribonucleases / chemical synthesis


  • Aminobutyrates
  • Bacterial Proteins
  • Bacteriocins
  • IgG Fc-binding protein, Streptococcus
  • Peptides
  • Proteins
  • microcin
  • Ribonucleases
  • Bacillus amyloliquefaciens ribonuclease
  • Cysteine