Journal article
Conformational analysis of XA and AX dipeptides in water by electronic circular dichroism and 1H NMR spectroscopy
The journal of physical chemistry. B, v 110(13), pp 6979-6986
06 Apr 2006
PMID: 16571011
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
We measured the temperature-dependent electronic circular dichroism (ECD) spectra of AX, XA, and XG dipeptides in D2O. The spectra of all XA and AX peptides indicate a substantial population of the polyproline II (PPII) conformation, while the ECD spectra of LG, KG, PG, and AG were found to be quantitatively different from the alanine-based dipeptides. Additional UV absorption data indicate that the ECD spectra of the XG peptides stem from electronic coupling between the peptide and the C-terminal group, and that spectral differences reflect different orientations of the latter. We also measured the 1H NMR spectra of the investigated dipeptides to determine the 3JHalphaNH coupling constants for the C-terminal residue. The observed temperature dependence of the ECD spectra and the respective room-temperature 3JHalphaNH coupling constants were analyzed by a two-state model encompassing PPII and a beta-like conformation. The PPII propensity of alanine in the XA series is only slightly modulated by the N-terminal side chain, and is larger than 50%. As compared to AA, XA peptides containing L, P, S, K V, E, T, and I all cause a relative stabilization of the extended beta-strand conformation. The PPII fractions of XA peptides varied between 0.64 for AA and 0.58 for DA, whereas the PPII fractions of AX peptides were much lower. From the investigated AX peptides, only AL and AQ showed the expected PPII propensity. We found that AT, AI, and AV clearly prefer an extended beta-strand conformation. A quantitative comparison of AA, AAA, and AAAA revealed a hierarchy AAAA > AAA approximately AA for the PPII population, in agreement with predictions from MD calculations and results from Raman optical activity studies (McColl et al. J. Am. Chem. Soc. 2004, 126, 5076).
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Details
- Title
- Conformational analysis of XA and AX dipeptides in water by electronic circular dichroism and 1H NMR spectroscopy
- Creators
- Andrew Hagarman - Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, USAThomas MeaseyRavi S DoddasomayajulaIsabelle DragomirFatma EkerKai GriebenowReinhard Schweitzer-Stenner
- Publication Details
- The journal of physical chemistry. B, v 110(13), pp 6979-6986
- Publisher
- American Chemical Society; Washington, DC
- Grant note
- P20 RR16439-01 / NCRR NIH HHS
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000236523100079
- Scopus ID
- 2-s2.0-33644675820
- Other Identifier
- 991014877996104721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Physical