Alamethicin, a hydrophobic peptide that is considered a paradigm for membrane channel formation, was uniformly labeled with 15N, reconstituted into oriented phosphatidylcholine bilayers at concentrations of 1 or 5 mol %, and investigated by solid-state NMR spectroscopy as a function of temperature. Whereas the peptide adopts a transmembrane alignment in POPC bilayers at all temperatures investigated, it switches from a transmembrane to an in-plane orientation in DPPC membranes when passing the phase transition temperature. This behavior can be explained by an increase in membrane hydrophobic thickness and the resulting hydrophobic mismatch condition.
View Article and Find Full Text PDFAmpullosporin A and alamethicin are two members of the peptaibol family of antimicrobial peptides. These compounds are produced by fungi and are characterized by a high content of hydrophobic amino acids, and in particular the alpha-tetrasubstituted amino acid residue ?-aminoisobutyric acid. Here ampullosporin A and alamethicin were uniformly labeled with (15)N, purified and reconstituted into oriented phophatidylcholine lipid bilayers and investigated by proton-decoupled (15)N and (31)P solid-state NMR spectroscopy.
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