Multiple Disulfide Bridge Peptides
Cysteine (Cys) residues in proteins and peptides are capable of forming disulfide bonds (i.e., disulfide bridges), a reversible covalent linkage between two side chain thiol groups. Disulfide bonds confer conformational constraints in linear peptide sequences that molecular rigidity and more stable secondary structures. Disulfide rich peptides are less prone to enzymatic degradation and can sometimes increase binding affinity to the corresponding receptor.
Conformationally stable disulfide-rich peptides has lead to many selective and potent classes of peptides. Toxin peptides from scorpions (e.g., chlorotoxin), cone snails (e.g., conotoxins), snakes, and spiders as well as host-defense peptides (e.g., α-defensins and β-defensins are important classes with diverse pharmacological applications. Conotoxins and chlorotoxins are potent blockers of ion channels and have been indicated as treatments for chronic pain and cancer.
Host defense peptides like α- and β-defensins have indications in cancer and antimicrobial therapeutics. Defensins contain stable β-sheet and α-helix secondary structures which are important for their pore-forming modes of action on the cellular membranes of bacteria. To learn more about antimicrobial peptides (AMPs) please read our AMP mini-review. Learn More »