1rkk
From Proteopedia
|
POLYPHEMUSIN I NMR SOLUTION STRUCTURE
Overview
The solution structure of polyphemusin I was determined using (1)H-NMR, spectroscopy. Polyphemusin I was found to be an amphipathic, beta-hairpin, connected by a type I' beta-turn. The 17 low-energy structures aligned, very well over the beta-sheet region while both termini were poorly, defined due in part to a hinge-like region centred in the molecule about, arginine residues 6 and 16. Conversely, a linear analogue, PM1-S, with all, cysteines simultaneously replaced with serine was found to be dynamic in, nature, and a lack of medium and long-range NOEs indicated that this, molecule displayed no favoured conformation. Circular dichroism (CD), spectroscopy confirmed that in solution, 50% trifluoroethanol (TFE) and in, the presence of liposomes, PM1-S remained unstructured. The antimicrobial, activity of PM1-S was found to be 4- to 16-fold less than that of, polyphemusin I and corresponded with a 4-fold reduction in bacterial, membrane depolarization. Both peptides were able to associate with lipid, bilayers in a similar fashion; however, PM1-S was completely unable to, translocate model membranes while polyphemusin I retained this activity., It was concluded that the disulfide-constrained, beta-sheet structure of, polyphemusin I is required for maximum antimicrobial activity. Disruption, of this structure results in reduced antimicrobial activity and completely, abolishes membrane translocation indicating that the linear PM1-S acts, through a different antimicrobial mechanism.
About this Structure
1RKK is a Protein complex structure of sequences from [1] with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
Structure-activity relationships for the beta-hairpin cationic antimicrobial peptide polyphemusin I., Powers JP, Rozek A, Hancock RE, Biochim Biophys Acta. 2004 May 6;1698(2):239-50. PMID:15134657
Page seeded by OCA on Wed Nov 21 01:40:02 2007
