Crystal structure of the channel-forming polypeptide antiamoebin in a membrane-mimetic environment.


Crystals of an ion-channel-forming peptaibol peptide in a partial membrane environment have been obtained by cocrystallizing antiamoebin with n-octanol. The antiamoebin molecule has a bent helical conformation very similar to that established for Leu-zervamicin, despite a significantly different sequence for residues 1-8. The bent helices assemble to form a polar channel in the shape of an hour glass that is quite comparable to that of Leu-zervamicin. The molecules of cocrystallized octanol are found in two different areas with respect to the assembly of peptide molecules. One octanol molecule mimics a membrane segment along the hydrophobic exterior of the channel assembly. The other octanol molecules fill the channel in such a way that their OH termini satisfy the C==O moieties directed into the interior of the channel. Structure parameters for C82 H27 N17 O20(.3) C8H18O are space group P2(1) 2(1) 2(1), a = 9.143(2) A, b = 28.590(8) A, c = 44.289(8) A, Z = 4, agreement factor R1 = 11.95% for 4,113 observed reflections [>4sigma(F)], resolution approximately 1.0 A.

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@article{Karle1998CrystalSO, title={Crystal structure of the channel-forming polypeptide antiamoebin in a membrane-mimetic environment.}, author={Isabella L . Karle and M A Perozzo and Vinod Kumar Mishra and Padmanabhan Balaram}, journal={Proceedings of the National Academy of Sciences of the United States of America}, year={1998}, volume={95 10}, pages={5501-4} }