A new perspective on β-sheet structures using vibrational Raman Optical Activity: from poly(l-lysine) to the prion protein

McColl, Iain H., Blanch, Ewan W., Gill, Andrew C. , Rhie, Alexandre G. O., Ritchie, Mark A., Hecht, Lutz, Nielsen, Kurt and Barron, Laurence D. (2003) A new perspective on β-sheet structures using vibrational Raman Optical Activity: from poly(l-lysine) to the prion protein. Journal of the American Chemical Society, 125 (33). pp. 10019-10026. ISSN 0002-7863

Full content URL: http://doi.org/10.1021/ja021464v

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Abstract

The vibrational Raman optical activity (ROA) spectrum of a polypeptide in a model beta-sheet conformation, that of poly(L-lysine), was measured for the first time, and the alpha-helix --> beta-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 a-helix or beta-sheet state were observed. The observation of ROA bands in the extended amide III region assigned to beta-turns suggests that, under our experimental conditions, beta-sheet poly(L-lysine) contains up-and-down antiparallel beta-sheets based on the hairpin motif. The ROA spectrum of beta-sheet poly(L-lysine) was compared with ROA data on a number of native proteins containing different types of beta-sheet. Amide I and amide II ROA band patterns observed in beta-sheet poly(L-lySine) are different from those observed in typical beta-sheet proteins and may be characteristic of an extended flat multistranded beta-sheet, which is unlike the more irregular and twisted beta-sheet found in most proteins. However, a reduced isoform of the truncated ovine prion protein PrP94-233 that is rich in beta-sheet shows amide I and amide II ROA bands similar to those of beta-sheet poly(L-lysine), which suggests that the C-terminal domain of the prion protein is able to support unusually flat beta-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.

Keywords:ploylysine, unfolded proteins, Ab-initio computation, Raman Spectroscopy, dynamics, conformations, prion, polyproline
Subjects:C Biological Sciences > C760 Biomolecular Science
F Physical Sciences > F165 Biomolecular Chemistry
Divisions:College of Science
ID Code:29572
Deposited On:15 Nov 2017 16:53

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