Abstract
A theoretical analysis is presented for the flattening of absorption and circular dichroic spectra of suspensions of membrane sheets containing proteins. Equations are presented to describe the dependence of this artifact on the size of the sheets. Values for the flattening coefficients QA and QB are calculated both as a function of absorptivity and sheet size. These studies show that sonication in an inadequate procedure for eliminating flattening in these samples.
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Selected References
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- DUYSENS L. N. The flattening of the absorption spectrum of suspensions, as compared to that of solutions. Biochim Biophys Acta. 1956 Jan;19(1):1–12. doi: 10.1016/0006-3002(56)90380-8. [DOI] [PubMed] [Google Scholar]
- Gordon D. J., Holzwarth G. Artifacts in the measured optic activity of membrane suspensions. Arch Biochem Biophys. 1971 Feb;142(2):481–488. doi: 10.1016/0003-9861(71)90511-x. [DOI] [PubMed] [Google Scholar]
- Mao D., Wallace B. A. Differential light scattering and absorption flattening optical effects are minimal in the circular dichroism spectra of small unilamellar vesicles. Biochemistry. 1984 Jun 5;23(12):2667–2673. doi: 10.1021/bi00307a020. [DOI] [PubMed] [Google Scholar]
- Nabedryk E., Bardin A. M., Breton J. Further characterization of protein secondary structures in purple membrane by circular dichroism and polarized infrared spectroscopies. Biophys J. 1985 Dec;48(6):873–876. doi: 10.1016/S0006-3495(85)83848-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schneider A. S., Harmatz D. An experimental method correcting for absorption flattening and scattering in suspensions of absorbing particles: circular dichroism and absorption spectra of hemoglobin in situ in red blood cells. Biochemistry. 1976 Sep 21;15(19):4158–4162. doi: 10.1021/bi00664a004. [DOI] [PubMed] [Google Scholar]
- Urry D. W. Protein conformation in biomembranes: optical rotation and absorption of membrane suspensions. Biochim Biophys Acta. 1972 Feb 14;265(1):115–168. doi: 10.1016/0304-4157(72)90021-4. [DOI] [PubMed] [Google Scholar]
- Wallace B. A., Mao D. Circular dichroism analyses of membrane proteins: an examination of differential light scattering and absorption flattening effects in large membrane vesicles and membrane sheets. Anal Biochem. 1984 Nov 1;142(2):317–328. doi: 10.1016/0003-2697(84)90471-8. [DOI] [PubMed] [Google Scholar]