Hepcidin-22 (human) and hepcidin-20 (human) have very similar peptide structure. The peptide sequence contains a large number of Cys. Therefore, this kind of peptide needs to have stable peptide bond to be more stable.The disulfide of peptide bond oxidized under natural conditions belongs to one of the most stable structures among all kinds of disulfide peptide bond. The stability of cyclized peptides formed by S-S peptide bond is much more stable than that of many amide bond, but much more stable than that of linear peptides.