A new perspective on β-sheet structures using vibrational raman optical activity: From poly(L-lysine) to the prion protein

Iain H. McColl, Ewan W. Blanch, Andrew C. Gill, Alexandre G O Rhie, Mark A. Ritchie, Lutz Hecht, Kurt Nielsen, Laurence D. Barron

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The vibrational Raman optical activity (ROA) spectrum of a polypeptide in a model β-sheet conformation, that of poly(L-lysine), was measured for the first time, and the α-helix → β-sheet transition monitored as a function of temperature in H2O and D2O. Although no significant population of a disordered backbone state was detected at intermediate temperatures, some side chain bands not present in either the α-helix or β-sheet state were observed. The observation of ROA bands in the extended amide III region assigned to β-turns suggests that, under our experimental conditions, β-sheet poly(L-lysine) contains up-and-down antiparallel β-sheets based on the hairpin motif. The ROA spectrum of β-sheet poly(L-lysine) was compared with ROA data on a number of native proteins containing different types of β-sheet. Amide I and amide II ROA band patterns observed in β-sheet poly(L-lysine) are different from those observed in typical β-sheet proteins and may be characteristic of an extended flat multistranded β-sheet, which is unlike the more irregular and twisted β-sheet found in most proteins. However, a reduced isoform of the truncated ovine prion protein PrP94-233 that is rich in β-sheet shows amide I and amide II ROA bands similar to those of β-sheet poly(L-lysine), which suggests that the C-terminal domain of the prion protein is able to support unusually flat β-sheets. A principal component analysis (PCA) that identifies protein structural types from ROA band patterns provides a useful representation of the structural relationships among the polypeptide and protein states considered in the study.
    Original languageEnglish
    Pages (from-to)10019-10026
    Number of pages7
    JournalJournal of the American Chemical Society
    Volume125
    Issue number33
    DOIs
    Publication statusPublished - 20 Aug 2003

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