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

McColl, Iain H. and Blanch, Ewan W. and Gill, Andrew C. and Rhie, Alexandre G. O. and Ritchie, Mark A. and Hecht, Lutz and 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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