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Publication Abstract from PubMed

Theta-defensins (theta-defensins) are ribosomally synthesised cyclic peptides found in the leukocytes of some primate species, and have promising applications as antimicrobial agents and scaffolds for peptide drugs. The cyclic cystine ladder motif, comprising a cyclic peptide backbone and three parallel disulfide bonds, is characteristic of theta-defensins. In this study, we explore the role of the cyclic peptide backbone and cystine ladder in the structure, stability, and activity of theta-defensins. theta-defensin analogues with different numbers and combinations of disulfide bonds were synthesised and characterised in terms of their NMR solution structures, serum and thermal stabilities, and their antibacterial and membrane-binding activities. Whereas the structures and stabilities of the peptides were primarily dependent on the number and position of the disulfide bonds, their antibacterial and membrane-binding properties were dependent on the cyclic backbone. The results provide insights into the mechanism of action of theta-defensins and illustrate the potential of theta-defensin analogues as scaffolds for peptide drug design.

The cyclic cystine ladder in theta-defensins is important for structure and stability, but not antibacterial activity.,Conibear AC, Rosengren KJ, Daly NL, Henriques ST, Craik DJ J Biol Chem. 2013 Feb 21. PMID:23430740^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.