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IR spectroscopy of isotope‐labeled helical peptides: Probing the effect of N‐acetylation on helix stability
Author(s) -
Decatur Sean M.
Publication year - 2000
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200009)54:3<180::aid-bip40>3.0.co;2-9
Subject(s) - chemistry , acetylation , stable isotope ratio , helix (gastropod) , isotope , spectroscopy , kinetic isotope effect , crystallography , deuterium , biochemistry , ecology , physics , quantum mechanics , biology , snail , gene
The effect of N‐acetylation on the conformation of alanine‐rich helical peptides is examined using isotope‐edited Fourier transform infrared (FTIR) spectroscopy. A series of peptides with sequence AA(AAKAA) 3 AAY has been prepared; each peptide incorporates four 13 C‐labeled alanines. These peptides have two amide I′ bands in their FTIR spectra: one corresponding to the 12 C amino acids, and one assigned to the 13 C amino acids. The intensity and frequency of the 13 C amide I′ band varies systematically with the position of the labels in the sequence and the presence or absence of an N‐acetyl capping group. The intensity of the 13 C amide I′ band correlates with helix stability at the labeled residues as predicted by thermodynamic models of the helix–coil transition. These results suggest that FTIR spectroscopy combined with specific isotope labeling can be used to dissect the conformation of helical peptides at the residue level. © 2000 John Wiley & Sons, Inc. Biopoly 54: 180–185, 2000