Cyclic Peptide
Also known as: cyclised peptide · macrocyclic peptide · peptide ring
A peptide whose chain is joined into a ring, giving greater stability and often better receptor selectivity.
A cyclic peptide has its chain closed into a loop — head-to-tail, or via a side-chain bridge such as a disulfide bond — rather than existing as a straight line with free ends.
Cyclisation removes the vulnerable termini and locks the molecule into a defined shape, which typically improves resistance to enzymes and can sharpen receptor selectivity. PT-141 (bremelanotide) is an example of a cyclic research peptide.
RELATED TERMS
Disulfide Bond
A covalent bridge between two cysteine side chains that locks a peptide’s three-dimensional shape in place.
N-terminus & C-terminus
The two ends of a peptide chain: the N-terminus has a free amino group, the C-terminus a free carboxyl group.
Half-Life
The time for a compound’s concentration to fall by half — a key determinant of dosing frequency in research.
PT-141
Bremelanotide — a melanocortin-receptor agonist studied for sexual arousal and libido via central nervous-system pathways.
Secondary & Tertiary Structure
The levels of peptide/protein organisation: sequence (primary), local folds (secondary), 3-D shape (tertiary), assembly (quaternary).
Educational content, not medical advice. All products supplied for research purposes only — not for human consumption.