Infrared dichroism of isotope-edited alpha-helices and beta-sheets.
Isotope editing of amide infrared bands not only localises secondary structural elements within the protein but also yields conformational information that is not available from the linear dichroism of aligned samples without isotope editing. The additional information that can be derived on the orientational distribution of alpha-helices in membranes by the combined use of different amide bands and several positions of labelling is presented here. Also, the relationship between the azimuthal orientation of the transition moment and the protein structure is treated explicitly. A comprehensive analysis of the infrared dichroism for beta-sheets and beta-barrels is given here, for the first time. The orientation of the individual transition moments in a beta-sheet that is essential for this analysis is derived for the different amide bands.
Marsh
Derek
D
Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie, 37070 Göttingen, Germany. dmarsh@gwdg.de
D000577:Amides / Q000737:chemistry*; D007259:Infrared Rays; D007554:Isotopes / Q000737:chemistry*; D008433:Mathematics; D008566:Membranes / Q000737:chemistry; D008954:Models, Biological; D017433:Protein Structure, Secondary; D013057:Spectrum Analysis / Q000379:methods*
D000577:Amides; D007554:Isotopes