20.500.12556/RUL-155243 Estimation of peptide helicity from circular dichroism using the ensemble model 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. circular dichroism helix-coil transition Lifson-Roig model helix ellipticity polylanine alpha-helix folding thermodynamics Markov modeling molecular structure optical properties peptides proteins spectroscopy cirkularni dikroizem prehod vijačnica-naključni klobčič Lifson-Roigov model eliptičnost alfa-vijačnice termodinamika zvitja true false true Angleški jezik Slovenski jezik Članek v reviji 2024-03-21 13:30:03 2024-03-21 13:30:04 2024-05-08 04:01:30 0000-00-00 00:00:00 2024 0 0 Str. 2652-2663 iss. 11 Vol. 128 21 Mar. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 577.322 1520-6106 10.1021/acs.jpcb.3c07511 189763843 zavrtanik-et-al-2024-estimation-of-peptide-helicity-from-circular-dichroism-using-the-ensemble-model.pdf zavrtanik-et-al-2024-estimation-of-peptide-helicity-from-circular-dichroism-using-the-ensemble-model.pdf 1 3C0DAF57D71F3D032BE25D4DE853B40A 3352679df3c185f5bd445129f4139ec03339ec84863ecf77f159d1b4c2d55e09 5a4e69f4-0c73-11ef-a791-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=183317 https://pubs.acs.org/doi/10.1021/acs.jpcb.3c07511 1 be835b34-e77e-11ee-922d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=182042 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0