title: A simple method for correction of circular dichroism spectra obtained from membrane-containing samples.
abstract: Circular dichroism (CD) spectroscopy is an important technique in structural biology for examining folding and conformational changes of proteins in solution. However, the use of CD spectroscopy in a membrane medium (and also in a nonhomogeneous medium) is limited by (i) high light scattering and (ii) differential scattering of incident left and right circularly polarized light, especially at shorter wavelengths (<200 nm). We report a novel methodology for estimating the distortion of CD spectra caused by light scattering for membrane-bound peptides and proteins. The method is applied to three proteins with very different secondary structures to illustrate the limits of its capabilities when calibrated with a simple soluble peptide ([Ac]ANLKALEAQKQKEQRQAAEELANAK[OH], standard peptide) with a balanced secondary structure. The method with this calibration standard was quite successful in estimating α-helix but more limited when it comes to proteins with very high β-sheet or β-turn content.
authors.affiliation: Department of Biochemistry and Biophysics and Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260, United States.
authors.forename: Hirak
authors.initials: H
authors.lastname: Chakraborty
authors.forename: Barry R
authors.initials: BR
authors.lastname: Lentz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism / Q000379:methods*; D018360:Crystallography, X-Ray; D006736:Horses; D008027:Light; D008563:Membrane Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009211:Myoglobin / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D014369:Tryptophan-tRNA Ligase / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D008563:Membrane Lipids; D008565:Membrane Proteins; D009211:Myoglobin; D010455:Peptides; D053835:Unilamellar Liposomes; D014369:Tryptophan-tRNA Ligase