Membrane-induced peptide structural changes monitored by infrared and circular dichroism spectroscopy.
As more peptide secondary structures deduced by infrared spectroscopy (IR) have been reported in the literature, there have been overlaps in assignments of elements of secondary structure to carbonyl vibrational frequencies. We have investigated this phenomenon with regards to the use of IR for monitoring membrane-induced structural changes using conformationally diverse peptides. These IR studies, complemented by circular dichroism (CD) experiments, revealed that peptide-solvent interactions can mask membrane-induced conformational changes monitored by IR. A structural transition from random coil to alpha-helix upon the binding of mastoparan X to a membrane was clearly observed by CD but obscured in the amide I region of the IR spectrum. In addition, unlike the buried helical peptides gramicidin D and P16 in micelles, the amide II peak for mastoparan X was absent, likely due to H-D exchange. This suggests information on the peptide's membrane-bound solvent accessibility could be obtained from this region of the spectrum.
Department of Chemistry, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928, USA.
Daniel J
DJ
Laird
Melinda M
MM
Mulvihill
Jennifer A Whiles
JA
Lillig
D000595:Amino Acid Sequence; D040761:Biomimetic Materials / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary / Q000187:drug effects; D012995:Solubility; D012997:Solvents / Q000494:pharmacology; D013055:Spectrophotometry, Infrared
D010455:Peptides; D012997:Solvents