Cyclization can improve conformational stability and protease resistance in research peptides. We support disulfide-bond formation, lactam bridges and head-to-tail cyclization.
Each cyclic project includes analytical confirmation of the intended linkage pattern wherever the chemistry allows.
Disulfide pairs should be numbered in the inquiry if more than two cysteines are present. Head-to-tail work needs a clear statement that both termini are free for cyclization and that no other reactive side chains should be left unprotected at that step.
A cyclic peptide is still a research reagent. Conformational constraint is a design choice, not a claim of drug-like stability in vivo.
When to choose which cycle
Disulfide cycles are the default for many native hormones. Head-to-tail cycles are used when a backbone constraint is the research question. Lactam staples sit between those options. See the cyclization article for the practical trade-offs.