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| Home > Publications database > Influence of alpha-Helical Content on the Thermodiffusion of Apomyoglobin |
| Conference Presentation (After Call) | FZJ-2026-02182 |
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2026
Abstract: Apo-myoglobin (Apo-Mb) is an extensively studied model system for investigating protein folding due to its distinct stable native, partially folded molten globule (MG), and unfolded states at acidic pH [1]. This study examines the impact of structural conformational changes on the thermodiffusive behavior of Apo-Mb using the infrared thermal diffusion forced Rayleigh scattering (TDFRS) technique [2]. The conformational states were modulated by varying pH and buffer conditions, with their structural changes confirmed via circular dichroism (CD) spectroscopy. The alpha-helical content decreased with decreasing pH. The thermodiffusion parameter \Delta S_T(\Delta T) , a measure of the temperature sensitivity of the Soret coefficient S_T, also showed a decrease, which is typically related to a decreasing hydrophilicity of the solute. Additionally, the buffer composition significantly influenced the thermodiffusive behavior: phosphate buffer promoted Apo-Mb aggregation through electrostatic screening, whereas acetate buffer favored Apo-Mb solubilization. Microsecond-long discrete protonation state constant pH molecular dynamics (CpHMD) simulations support the experimentally observed, pH- and buffer-dependent changes in alpha-helical content and highlight the differences in protein-buffer interactions for phosphate buffer versus acetate buffer. In conclusion, a strong correlation was observed between the thermodiffusion parameter \Delta S_T(\Delta T) and the alpha-helical content, with \Delta S_T(\Delta T) increasing alongside hydrophilicity and alpha-helical content. These findings highlight the role of structural conformation and buffer environment in modulating the thermodiffusive properties of proteins.Literature:[1] A. Stadler et al. PCCP 2016, 18, 21527. [2] B.A. Rudani et al., Langmuir 2025, 41, 28322.
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