Mobility and solvent exposure of aromatic residues in bacteriorhodopsin investigated by 1 H-NMR and photo-CIDNP-NMR spectroscopy

The secondary structure of bacteriorhodopsin in organic solution. A Fourier transform infrared study

Fourier transform infrared spectroscopy is used to estimate the secondary structure of bacteriorhodopsin dissolved in chloroform-methanol (1:1 v/v), 0.1 M LiClO4. Curve-fitting of the deconvolved spectra in the amide I region shows that the total content of alpha-helices, reverse turns and beta-sheets are similar to the native state. However, the alpha II-helices, which are the major helical class in native bacteriorhodopsin, are greatly decreased in the solubilized sample. Similarly, the reverse turns and the beta-sheets are strongly altered.

NMR studies of retinal proteins

A review is given of the use of nuclear magnetic resonance (NMR) spectroscopy to study bacteriorhodopsin and bovine rhodopsin. Solution and solid-state approaches are included. The studies of the bacterial proton pump examine the chromophore, the peptide backbone, and the protein side chains. The studies of the bovine visual pigment are limited to the chromophore. Various forms of each pigment are considered. Both structural and dynamic features are addressed.