Conference Presentation (After Call)

FZJ-2026-03948

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Influence of alpha-Helical Content on the Thermodiffusion of Apomyoglobin

Rudani, B. (Corresponding author)FZJ* ; Docter, S.FZJ* ; Schott-Verdugo, S.FZJ* ; Buitenhuis, J.FZJ* ; Stadler, A.FZJ* ; Gohlke, H.FZJ* ; Wiegand, S.FZJ*

2026

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Please use a persistent id in citations: doi:10.34734/FZJ-2026-03948

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 deltaS_T(deltaT), 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 deltaS_T(deltaT) and the alpha-helical content, with deltaS_T(deltaT) 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.

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Contributing Institute(s):

1. Biomakromolekulare Systeme und Prozesse (IBI-4)

Research Program(s):

1. 5241 - Molecular Information Processing in Cellular Systems (POF4-524) (POF4-524)

Appears in the scientific report 2026

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Database coverage:

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