Time-Resolved Optical Kerr-Effect Spectroscopy of Low-Frequency Dynamics in Di-l-alanine, Poly-l-alanine, and Lysozyme in Solution

• Published in: Journal of the American Chemical Society Vol. 124; no. 41; pp. 12110 - 12111
• Main Authors: Giraud, Gerard, Wynne, Klaas
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16.10.2002
• Subjects: Alanine - analogs & derivatives; Alanine - chemistry; Analytical biochemistry: general aspects, technics, instrumentation; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Dipeptides - chemistry; Fundamental and applied biological sciences. Psychology; Kinetics; Muramidase - chemistry; Muramidase - metabolism; Peptides - chemistry; Peptides - metabolism; Protein Structure, Secondary; Solutions; Spectrum Analysis, Raman - methods; Time resolution; Alanine; Chemistry; Enzyme; Dynamics; Glycosidases; Kerr electrooptical effect; Hydrolases; O-Glycosidases; Spectroscopical observation; Lysozyme; Solution
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja027801h

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 α-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 α-helix. The mostly α-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.