Determination of the secondary structure of proteins from the amide I band of the laser Raman spectrum

Robert W. Williams, A. Keith Dunker

Research output: Contribution to journalArticle

126 Scopus citations


The amide I band in the laser Raman spectrum of proteins has been resolved into six components, each representing residues in a different type of secondary structure. These structure types are ordered or bihydrogen-bonded helix (believed to be located in the center of helical segments), disordered or monohydrogen-bonded helix (believed to be located at the ends of helical segments), antiparallel beta sheet, parallel beta sheet, reverse turn, and undefined. The Raman spectrum representing 100% of each type of residue conformation has been computed from the solvent-subtracted Raman spectra of ten proteins with known secondary structure, plus poly-l-lysine using a least-squares solution of the overdetermined system of equations. Linear combinations of these reference spectra were then fitted to the experimental amide I spectra of these and other proteins to estimate the fractions of residues in these conformations. Statistical tests suggest that the discrimination between bihydrogen-bonded helix and monohydrogen-bonded helix is significant as is the discrimination between parallel and antiparallel β-sheet. However, the discrimination between random structure and turns has not yet been accomplished by these studies. The absolute difference between X-ray and Raman estimates of structure for 17 protein samples is generally less than 6%. We conclude that detailed and reasonably accurate estimates of secondary structure can be derived from the amide I spectra of proteins.

Original languageEnglish (US)
Pages (from-to)783-813
Number of pages31
JournalJournal of molecular biology
Issue number4
StatePublished - Nov 15 1981
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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