Secondary structure and dosage of soluble and membrane proteins by attenuated total reflection Fourier-transform infrared spectroscopy on hydrated films

Eur J Biochem. 1990 Oct 24;193(2):409-20. doi: 10.1111/j.1432-1033.1990.tb19354.x.

Abstract

Attenuated total reflection Fourier-transform infrared spectroscopy of thin hydrated films of soluble and membrane protein included in a phospholipid bilayer is shown to provide useful information as to the secondary structure of the protein. The analysis of the amide I band of deuterated samples by Fourier self-deconvolution followed by a curve fitting was performed by a new procedure in which all the input parameters are generated by the computer rather than by the investigator. The results of this analysis provide a correct estimation of the alpha-helix and beta-sheet structure content with a standard deviation of 8.6% when X-ray structures are taken as a reference. We also show that the orientation of the different secondary structures resolved by the Fourier self-deconvolution/curve-fitting procedure and of the phospholipid acyl chains can be simultaneously evaluated for membrane proteins reconstituted in a lipid bilayer. Of special interest for reconstitution of membrane proteins, the lipid/protein ratio can be accurately and quickly determined from the infrared spectrum.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electronic Data Processing
  • Fourier Analysis*
  • Membrane Proteins / chemistry*
  • Phospholipids
  • Protein Conformation*
  • Spectrophotometry, Infrared / methods

Substances

  • Membrane Proteins
  • Phospholipids