Time-resolved optical Kerr-effect spectroscopy of low-frequency dynamics in Di-L-alanine, poly-L-alanine, and lysozyme in solution.
The low-frequency spectra of peptides and proteins in solution have been investigated with optical heterodyne-detected Raman-induced Kerr-effect spectroscopy. Spectra were obtained for di-l-alanine ALA(2) and poly-l-alanine (PLA) in dichloroacetic acid solution. The conformational dependence of those spectra at low frequency has been analyzed. ALA(2) displays a band centered at 50 cm-1, whereas the alpha-helical PLA shows two shoulders at 60 and 140 cm-1. The similarity of the spectral features observed in PLA to those in water can be explained by analogous acoustic translational modes in the hydrogen network of the PLA alpha-helix. The mostly alpha-helical protein lysozyme in aqueous solution has also been investigated and showed significantly more structure with modes at 10, 35, 73, 106, and 164 cm-1.
Giraud
Gerard
G
Department of Physics, University of Strathclyde, Glasgow G4 0NG, Scotland.
Wynne
Klaas
K
D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D007700:Kinetics; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D012996:Solutions; D013059:Spectrum Analysis, Raman / Q000379:methods*
D004151:Dipeptides; D010455:Peptides; D012996:Solutions; C019529:polyalanine; D009113:Muramidase; D000409:Alanine