TY  - JOUR
AU  - Rudani, Binny A.
AU  - Docter, Steffen
AU  - Schott-Verdugo, Stephan
AU  - Buitenhuis, Johan
AU  - Stadler, Andreas M.
AU  - Gohlke, Holger
AU  - Wiegand, Simone
TI  - Influence of α-Helical Content on the Thermodiffusion of Apomyoglobin
JO  - Langmuir
VL  - 41
IS  - 42
SN  - 0743-7463
CY  - Washington, DC
PB  - ACS Publ.
M1  - FZJ-2025-04174
SP  - 28322–28334
PY  - 2025
N1  - This is an OA article.
AB  - 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 {\color{black} unfolded} states at acidic pH. 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. 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 $\Delta S_{\mathrm{T}}(\Delta T)$, a measure of the temperature sensitivity of the Soret coefficient $S_{\mathrm{T}}$, 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 $\Delta S_{\mathrm{T}}(\Delta T)$ and the $\alpha$-helical content, with $\Delta S_{\mathrm{T}}(\Delta T)$ 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.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1021/acs.langmuir.5c02797
UR  - https://juser.fz-juelich.de/record/1047243
ER  -