β‐Sheet and associated turn signatures in vibrational Raman optical activity spectra of proteins

Open Access
Publisher Website
Google Scholar
Abstract
We have measured the aqueous solution vibrational Raman optical activity (ROA) spectra of concanavalin A, α‐chymotrypsin, and β‐lactoglobulin, all of which are rich in β‐sheet, together with that of the model β‐turn peptide L‐pro‐L‐leu‐gly‐NH2. Possible ROA signatures of antiparallel β‐sheet include a strong sharp positive band at ∼ 1,313 cm” associated with backbone amide III CαH and NH deformations, and an amide I couplet, negative at low wavenumber and positive at high, centered at ∼1,658 cm−1. Negative ROA bands in the range ∼1,340‐1,380 cm−1, which might originate in glycine CH2 deformations, appear to be characteristic of β‐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.

This publication has 20 references indexed in Scilit: