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Protein stability induced by ligand binding correlates with changes in protein flexibility
María Soledad Celej1, Guillermo G Montich, Gerardo D Fidelio
1Centro de Investigaciones en Química Biológica de Córdoba-CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Pabellón Argentina, Ciudad Universitaria, 5000 Córdoba, Argentina.
Protein Science : a Publication of the Protein Society
|June 26, 2003
Summary
Ligand binding alters protein stability and flexibility. Anilinonaphthalene sulfonate derivatives (ANS) binding to bovine serum albumin (BSA) showed varying effects, with bis-ANS inducing a molten globule-like state and increased flexibility.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Dynamics
Background:
- Ligand-protein interactions critically influence protein thermal stability and conformational dynamics.
- Understanding these changes is key to elucidating molecular mechanisms in biological systems.
Purpose of the Study:
- To investigate the impact of different anilinonaphthalene sulfonate (ANS) derivatives on the stability, conformation, and dynamics of bovine serum albumin (BSA).
- To correlate changes in protein flexibility with observed stability alterations upon ligand binding.
Main Methods:
- Differential scanning calorimetry (DSC) and fluorescence spectroscopy for protein stability assessment.
- Circular dichroism (CD) and infrared (IR) spectroscopy, including hydrogen/deuterium exchange kinetics, for conformational analysis.
Main Results:
- Ligand binding order of calorimetric midpoint of denaturation: 1,8-ANS-BSA > 2,6-ANS-BSA > free BSA >> bis-ANS-BSA.
- 1,8-ANS and 2,6-ANS minimally affected BSA secondary structure, while bis-ANS induced distorted alpha-helices and increased disorder.
- Protein flexibility order: 1,8-ANS-BSA < 2,6-ANS-BSA < free BSA << bis-ANS-BSA, demonstrating a stability-flexibility correlation.
Conclusions:
- The binding of ANS derivatives to BSA induces distinct conformational states, ranging from minor modifications to a molten globule-like state with bis-ANS.
- The study identifies five distinguishable conformers within the BSA conformational ensemble based on ligand interaction and temperature.
- Ligand type, concentration, and temperature collectively dictate the population of these conformers, supporting the binding landscape model.