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New page: left|200px<br /><applet load="1rkk" size="450" color="white" frame="true" align="right" spinBox="true" caption="1rkk" /> '''POLYPHEMUSIN I NMR SOLUTION STRUCTURE'''<br ...
 
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[[Image:1rkk.gif|left|200px]]<br /><applet load="1rkk" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1rkk" />
'''POLYPHEMUSIN I NMR SOLUTION STRUCTURE'''<br />


==Overview==
==POLYPHEMUSIN I NMR SOLUTION STRUCTURE==
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.
<StructureSection load='1rkk' size='340' side='right'caption='[[1rkk]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1rkk]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1RKK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1RKK FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NH2:AMINO+GROUP'>NH2</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1rkk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1rkk OCA], [https://pdbe.org/1rkk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1rkk RCSB], [https://www.ebi.ac.uk/pdbsum/1rkk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1rkk ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PPM1_LIMPO PPM1_LIMPO] Significantly inhibits the growth of Gram-negative and Gram-positive bacteria.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
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==
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<ref>PMID:15134657</ref>
1RKK is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with NH2 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1RKK OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15134657 15134657]
</div>
[[Category: Protein complex]]
<div class="pdbe-citations 1rkk" style="background-color:#fffaf0;"></div>
[[Category: Hancock, R.E.W.]]
== References ==
[[Category: Powers, J.P.S.]]
<references/>
[[Category: Rozek, A.]]
__TOC__
[[Category: NH2]]
</StructureSection>
[[Category: anti-microbial peptide]]
[[Category: Large Structures]]
[[Category: beta hairpin]]
[[Category: Synthetic construct]]
[[Category: disulfide bridge]]
[[Category: Hancock REW]]
[[Category: polyphemusin]]
[[Category: Powers JPS]]
 
[[Category: Rozek A]]
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 01:40:02 2007''
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