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UV resonance raman spectroscopy monitors polyglutamine backbone and side chain hydrogen bonding and fibrillization

Xiong, K and Punihaole, D and Asher, SA (2012) UV resonance raman spectroscopy monitors polyglutamine backbone and side chain hydrogen bonding and fibrillization. Biochemistry, 51 (29). 5822 - 5830. ISSN 0006-2960

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We utilize 198 and 204 nm excited UV resonance Raman spectroscopy (UVRR) and circular dichroism spectroscopy (CD) to monitor the backbone conformation and the Gln side chain hydrogen bonding (HB) of a short, mainly polyGln peptide with a D2Q10K2 sequence (Q10). We measured the UVRR spectra of valeramide to determine the dependence of the primary amide vibrations on amide HB. We observe that a nondisaggregated Q10 (NDQ10) solution (prepared by directly dissolving the original synthesized peptide in pure water) exists in a β-sheet conformation, where the Gln side chains form hydrogen bonds to either the backbone or other Gln side chains. At 60 °C, these solutions readily form amyloid fibrils. We used the polyGln disaggregation protocol of Wetzel et al. [Wetzel, R., et al. (2006) Methods Enzymol.413, 34-74] to dissolve the Q10 β-sheet aggregates. We observe that the disaggregated Q10 (DQ10) solutions adopt PPII-like and 2.51-helix conformations where the Gln side chains form hydrogen bonds with water. In contrast, these samples do not form fibrils. The NDQ10 β-sheet solution structure is essentially identical to that found in the NDQ10 solid formed upon evaporation of the solution. The DQ10 PPII and 2.51-helix solution structure is essentially identical to that in the DQ10 solid. Although the NDQ10 solution readily forms fibrils when heated, the DQ10 solution does not form fibrils unless seeded with the NDQ10 solution. This result demonstrates very high activation barriers between these solution conformations. The NDQ10 fibril secondary structure is essentially identical to that of the NDQ10 solution, except that the NDQ10 fibril backbone conformational distribution is narrower than in the dissolved species. The NDQ10 fibril Gln side chain geometry is more constrained than when NDQ10 is in solution. The NDQ10 fibril structure is identical to that of the DQ10 fibril seeded by the NDQ10 solution. © 2012 American Chemical Society.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Xiong, K
Punihaole, D
Asher, SAasher@pitt.eduASHER
Date: 24 July 2012
Date Type: Publication
Journal or Publication Title: Biochemistry
Volume: 51
Number: 29
Page Range: 5822 - 5830
DOI or Unique Handle: 10.1021/bi300551b
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0006-2960
MeSH Headings: Amyloid--chemistry; Amyloid--ultrastructure; Circular Dichroism; Hydrogen Bonding; Peptides--chemistry; Protein Structure, Secondary; Spectrum Analysis, Raman--methods; Ultraviolet Rays; Valerates--chemistry
Other ID: NLM NIHMS393157, NLM PMC3415266
PubMed Central ID: PMC3415266
PubMed ID: 22746095
Date Deposited: 15 Feb 2013 14:26
Last Modified: 22 Jun 2021 13:55


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