Beta-sheet and associated turn signatures in vibrational Raman optical activity spectra of proteins.
We have measured the aqueous solution vibrational Raman optical activity (ROA) spectra of concanavalin A, alpha-chymotrypsin, and beta-lactoglobulin, all of which are rich in beta-sheet, together with that of the model beta-turn peptide L-pro-L-leu-gly-NH2. Possible ROA signatures of antiparallel beta-sheet include a strong sharp positive band at approximately 1,313 cm-1 associated with backbone amide III C alpha H and NH deformations, and an amide I couplet, negative at low wavenumber and positive at high, centered at approximately 1,658 cm-1. Negative ROA bands in the range approximately 1,340-1,380 cm-1, which might originate in glycine CH2 deformations, appear to be characteristic of beta-turns. Our results provide further evidence that ROA is a more incisive probe of protein conformation than conventional vibrational spectroscopy, infrared, or Raman, because only those few vibrational coordinates within a given normal mode that sample the skeletal chirality directly contribute to the corresponding ROA band intensity.
Wen
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Chemistry Department, The University, Glasgow, United Kingdom.
Hecht
L
L
Barron
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LD
D000595:Amino Acid Sequence; D009075:MSH Release-Inhibiting Hormone / Q000737:chemistry; D008956:Models, Chemical; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014732:Vibration
D011506:Proteins; D009075:MSH Release-Inhibiting Hormone