Circular dichroism and conformational analysis of the membrane-modifying peptide -N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu-(OBzl)-Gln-OMe with respect to alamethicin

The conformational analysis of the CD spectrum is reported for the synthetic and membrane‐modifying nonadecapeptide analog of alamethicin N‐t‐Boc‐(Aib‐L‐Ala)5‐Gly‐Ala‐Aib‐Pro‐Ala‐Aib‐Aib‐Glu(OBzl)‐ Gln‐OMe. The CD data are evaluated according to three different methods and are discussed with respect to those obtained from natural alamethicin and suitable models such as N‐t‐Boc‐(Aib‐L‐Ala)7‐OPOE, fragments of the synthetic nonadecapeptide, and the hexadecapeptide N‐t‐Boc‐(Aib‐L‐Ala)5‐Pro‐Ala‐Aib‐Aib‐Glu(OBzl)‐Gln‐OMe. The synthetic nonadecapeptide with the longer helical region exhibits membrane activities comparable to those of alamethicin, whereas the hexadecapeptide with the shorter helix is inactive.