1qvk
From Proteopedia
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Structure of the antimicrobial hexapeptide cyc-(RRWWRF) bound to DPC micelles
Overview
Antimicrobial, cationic peptides are abundant throughout nature as part of, many organisms' defence against microorganisms. They exhibit a large, variety of sequences and structural motifs and are thought to act by, rupturing the bacterial membrane. Several models based on biophysical, experiments have been proposed for their mechanism of action. Here we, present the NMR-determined structure of the cyclic, cationic antimicrobial, peptide cyclo(RRWWRF) both free in aqueous solution and bound to detergent, micelles. The peptide has a rather flexible but ordered structure in, water. A distinct structure is formed when the peptide is bound to a, detergent micelle. The structures in neutral and negatively charged, micelles are nearly identical but differ from that in aqueous solution., The orientation of the amino acid side chains creates an amphipathic, molecule with the peptide backbone forming the hydrophilic part. The, orientation of the peptide in the micelle was determined by using NOEs and, paramagnetic agents. The peptide is oriented mainly parallel to the, micelle surface in both detergents. Substitution of the arginine and, tryptophan residues is known to influence the antimicrobial activity., Therefore the structure of the micelle-bound analogues cyclo(RRYYRF), cyclo(KKWWKF) and cyclo(RRNalNalRF) were also determined. They exhibit, remarkable similarities in backbone conformation and side-chain, orientation. The structure of these peptides allows the side-chain, properties to be correlated to biological activity.
About this Structure
1QVK is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Structure of the antimicrobial, cationic hexapeptide cyclo(RRWWRF) and its analogues in solution and bound to detergent micelles., Appelt C, Wessolowski A, Soderhall JA, Dathe M, Schmieder P, Chembiochem. 2005 Sep;6(9):1654-62. PMID:16075425
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