NMR structure of the channel-former zervamicin IIB in isotropic solvents.

Spatial structure of the membrane channel-forming hexadecapeptide, zervamicin IIB, was studied by NMR spectroscopy in mixed solvents of different polarity ranging from CDCl3/CD3OH (9:1, v/v) to CD3OH/H2O (1:1, v/v). The results show that in all solvents used the peptide has a very similar structure that is a bent amphiphilic helix with a mean backbone root mean square deviation (rmsd) value of ca. 0.3 A. Side chains of Trp1, Ile2, Gln3, Ile5 and Thr6 are mobile. The results are discussed in relation to the validity of the obtained structure to serve as a building block of zervamicin IIB ion channels.