Discloses a proislet peptide comprising an optimization modification, wherein said optimization modification is a C-terminal cysteine residue, wherein said peptide is selected from: modified HIP1,HIP2,HIP3, human REG3A/REG3G, human REGlA/REGIB, human REG4, hamster INGAP, hamster REG2, rodent REG3G, rat REGl, rat PAP/REG3B, rat PAP3, mouse REG l/REG2/REG3A/REG3B /REG3G/REG3S/REG4 peptides and bovine PTP peptide. Further discloses a optimization modification that is N-terminal acetyl group and a C terminal cysteine residue. Further disclosed is the use of disclosed peptides in the manufacture of a pharmaceutical composition for treating a pathology associated with impaired pancreatic function (e.g. diabetes).
