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Raman Spectroscopic Characterization of Secondary Structure in Natively Unfolded Proteins: α-Synuclein
Nakul C. Maiti, Mihaela M. Apetri, Michael G. Zagorski, PAUL R. CAREY, Vernon E. Anderson. Journal of the American Chemical Society, 2004-02-04
Topic: Disease mechanisms in lab and animal studies
The application of Raman spectroscopy to characterize natively unfolded proteins has been underdeveloped, even though it has significant technical advantages. We propose that a simple three-component band fitting of the amide I region can assist in the conformational characterization of the ensemble of structures present in natively unfolded proteins. The Raman spectra of alpha-synuclein, a prototypical natively unfolded protein, were obtained in the presence and absence of methanol, sodium dodecyl sulfate (SDS), and hexafluoro-2-propanol (HFIP). Consistent with previous CD studies, the secondary structure becomes largely alpha-helical in HFIP and SDS and predominantly beta-sheet in 25% methanol in water. In SDS, an increase in alpha-helical conformation is indicated by the predominant Raman amide I marker band at 1654 cm(-1) and the typical double minimum in the CD spectrum. In 25% HFIP the amide I Raman marker band appears at 1653 cm(-1) with a peak width at half-height of approximately 33 cm(-1), and in 25% methanol the amide I Raman band shifts to 1667 cm(-1) with a peak width at half-height of approximately 26 cm(-1). These well-characterized structural states provide the unequivocal assignment of amide I marker bands in the Raman spectrum of alpha-synuclein and by extrapolation to other natively unfolded proteins. The Raman spectrum of monomeric alpha-synuclein in aqueous solution suggests that the peptide bonds are distributed in both the alpha-helical and extended beta-regions of Ramachandran space. A higher frequency feature of the alpha-synuclein Raman amide I band resembles the Raman amide I band of ionized polyglutamate and polylysine, peptides which adopt a polyproline II helical conformation. Thus, a three-component band fitting is used to characterize the Raman amide I band of alpha-synuclein, phosvitin, alpha-casein, beta-casein, and the non-A beta component (NAC) of Alzheimer's plaque. These analyses demonstrate the ability of Raman spectroscopy to characterize the ensemble of secondary structures present in natively unfolded proteins.
Key findings
- The application of Raman spectroscopy to characterize natively unfolded proteins has been underdeveloped, even though it has significant technical advantages.
- The Raman spectrum of monomeric alpha-synuclein in aqueous solution suggests that the peptide bonds are distributed in both the alpha-helical and extended beta-regions of Ramachandran space.
Study details
- Evidence strengthLow
How this study scored 36/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 21 of the 58 points we could judge it on, which is 36 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Journal of the American Chemical Society) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2004 — older than 20 years, still counted |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 14982446) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 21 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 21 of the 58 points we could judge it on is 36 out of 100. |
| Total | 36 / 100 | — |
What each of these 20 components measures, and what this score is not →
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APA 7th
Maiti, N. C., Apetri, M. M., Zagorski, M. G., CAREY, P. A. U. L. R., & Anderson, V. E. (2004). Raman Spectroscopic Characterization of Secondary Structure in Natively Unfolded Proteins: α-Synuclein. Journal of the American Chemical Society. https://doi.org/10.1021/ja0356176
Vancouver
Maiti NC, Apetri MM, Zagorski MG, CAREY PAULR, Anderson VE. Raman Spectroscopic Characterization of Secondary Structure in Natively Unfolded Proteins: α-Synuclein. Journal of the American Chemical Society. 2004. doi:10.1021/ja0356176. PMID: 14982446.
BibTeX
@article{maiti2004-14982446,
author = {Maiti, Nakul C. and Apetri, Mihaela M. and Zagorski, Michael G. and CAREY, PAUL R. and Anderson, Vernon E.},
title = {{Raman Spectroscopic Characterization of Secondary Structure in Natively Unfolded Proteins: α-Synuclein}},
journal = {Journal of the American Chemical Society},
year = {2004},
doi = {10.1021/ja0356176},
pmid = {14982446},
url = {https://doi.org/10.1021/ja0356176}
}
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