1. Multiple disulfide bonds
The synthesis of peptides containing multiple disulfide bonds can be challenging. This is due to the fact that multiple disulfide bonds can form randomly within any peptides that contain multiple cysteines. Few companies around the world offer multi- disulfide bond peptide synthesis, and none of them can synthesize peptides with more. GenScript, however, has developed two methods to synthesize peptides containing multiple disulfide bonds.
The first of these is a stepwise oxidation method utilizing different protecting groups to protect each cysteine pair during the Fmoc SPPS synthesis process. Different deprotecting conditions are used to deprotect each protecting group. These are carefully selected based on the specific needs of the client's project. With subsequent stepwise oxidizations of the disulfide bonds during the liquid phase, we can accurately synthesize peptides with more than two disulfide bonds with great accuracy.
The second method requires single-step oxidation of all of the cysteines of the peptide in liquid phase, to form a peptide containing native multiple disulfide bonds. Zymohydrolysis is subsequently employed to orient the position of disulfide bonds.
Case study: Peptide A
Sequence: H - Cys - Asn - Cys - ... ... ... - Cys - ... ... ... - Cys - ... ... ... - NH2
Disulfide bridge: 1 - 11, 3 - 15