Uroš Zavrtanik (Author), Jurij Lah (Author), San Hadži (Author)

Abstract

An established method for the quantitation of the helix content in peptides using circular dichroism (CD) relies on the linear spectroscopic model. This model assumes an average value of the helix-length correction for all peptide conformers, irrespective of the length of the helical segment. Here we assess the validity of this approximation and introduce a more physically realistic ensemble-based analysis of the CD signal in which the length correction is assigned specifically to each ensemble conformer. We demonstrate that the linear model underestimates peptide helicity, with the difference depending on the ensemble composition. We developed a computer program that implements the ensemble model to estimate the peptide helicity. Using this model and the CD data set covering a broad range of helicities, we recalibrate CD baseline parameters and redetermine helix–coil parameters for the alanine-rich peptide. We show that the ensemble model leverages small differences in signal between conformers to extract more information from the experimental data, enabling the determination of several poorly defined quantities, such as the nucleation constant and heat capacity change associated with helix folding. Overall, the presented ensemble-based treatment of the CD signal, together with the recalibrated values of the spectroscopic baseline parameters, provides a coherent framework for the analysis of the peptide helix content.

Keywords

cirkularni dikroizem;prehod vijačnica-naključni klobčič;Lifson-Roigov model;eliptičnost alfa-vijačnice;termodinamika zvitja;circular dichroism;helix-coil transition;Lifson-Roig model;helix ellipticity;polylanine alpha-helix folding thermodynamics;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
UDC: 577.322
COBISS: 189763843 Link will open in a new window
ISSN: 1520-6106
Views: 106
Downloads: 150
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

Secondary language: Slovenian
Secondary keywords: cirkularni dikroizem;prehod vijačnica-naključni klobčič;Lifson-Roigov model;eliptičnost alfa-vijačnice;termodinamika zvitja;
Type (COBISS): Article
Pages: str. 2652-2663
Volume: ǂVol. ǂ128
Issue: ǂiss. ǂ11
Chronology: 21 Mar. 2024
DOI: 10.1021/acs.jpcb.3c07511
ID: 23204589