## Effects of N-terminus substitution on the structure and spectroscopy of gas-phase helices

Because of the importance of helices in the secondary structure of proteins, we have undertaken a study of their spectroscopy, fragmentation patterns and conformations in the gas phase. In this work, we describe the effects of substitution at the N-terminus of polyalanine helices capped with a lysine at the C-terminus, namely Ac-Phe-(Ala)(10)-Lys-H+, Phe-(Ala)(10)-Lys-H-divided by, and H+-Phe-(Ala)(10)-Lys-H+. Acetylation of the N-terminus has very little effect on the spectroscopy and structure, but protonation of the N-terminus changes the infrared spectrum in such a way that we believe it may also change the structure of the peptide. The ultraviolet spectroscopy and fragmentation, on the other hand, are insensitive to either acetylation or protonation.

Published in:
Chimia, 62, 240-243
Year:
2008
Keywords:
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