Related Experiment Video
Updated: Sep 21, 2025

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Reprint of: Fourier Transform Infrared Study of Proteins with Parallel β-Chains
1Eastern Regional Research Center, United States Department of Agriculture, 600 East Mermaid Lane, Philadelphia, Pennsylvania, 19118.
Abstract:
Deconvolved and second derivative Fourier transform infrared spectra of the proteins flavodoxin and triosephosphate isomerase have been obtained in the 1600 to 1700 cm-1 (amide I) region. To our knowledge these results provide the first experimental infrared data on proteins with parallel β-chains. Characteristic absorption bands for the parallel β-segments are observed at 1626-1639 cm-1 (strong) and close to 1675 cm-1 (weak). Previous theoretical studies based on hypothetical models with large, regular β-sheets had suggested bands close to 1650 and 1666 cm-1. Our new assignments were confirmed by band area measurements, which yield conformational information in good agreement with results from X-ray diffraction data. The spectra were compared with corresponding spectra of concanavalin A and carboxypeptidase A. The first contains only antiparallel β-segments, the second "mixed" β-segments, with some strands lying antiparallel and others parallel. None of the observed amide I band frequencies assigned to parallel β-chains occurs in the 1650 cm-1 region associated with helical segments.
Related Concept Videos
IR Frequency Region: Fingerprint Region
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
IR Frequency Region: X–H Stretching
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
IR Spectrum Peak Broadening: Hydrogen Bonding
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...

