Protein stability induced by ligand binding correlates with changes in protein flexibility.


The interaction between ligands and proteins usually induces changes in protein thermal stability with modifications in the midpoint denaturation temperature, enthalpy of unfolding, and heat capacity. These modifications are due to the coupling of unfolding with binding equilibrium. Furthermore, they can be attained by changes in protein structure and conformational flexibility induced by ligand interaction. To study these effects we have used bovine serum albumin (BSA) interacting with three different anilinonaphthalene sulfonate derivatives (ANS). These ligands have different effects on protein stability, conformation, and dynamics. Protein stability was studied by differential scanning calorimetry and fluorescence spectroscopy, whereas conformational changes were detected by circular dichroism and infrared spectroscopy including kinetics of hydrogen/deuterium exchange. The order of calorimetric midpoint of denaturation was: 1,8-ANS-BSA > 2,6-ANS-BSA > free BSA > (nondetected) bis-ANS-BSA. Both 1,8-ANS and 2,6-ANS did not substantially modify the secondary structure of BSA, whereas bis-ANS induced a distorted alpha-helix conformation with an increase of disordered structure. Protein flexibility followed the order: 1,8-ANS-BSA < 2,6-ANS-BSA < free BSA < bis-ANS-BSA, indicating a clear correlation between stability and conformational flexibility. The structure induced by an excess of bis-ANS to BSA is compatible with a molten globule-like state. Within the context of the binding landscape model, we have distinguished five conformers (identified by subscript): BSA(1,8-ANS), BSA(2,6-ANS), BSA(free), BSA(bis-ANS), and BSA(unfolded) among the large number of possible states of the conformational dynamic ensemble. The relative population of each distinguishable conformer depends on the type and concentration of ligand and the temperature of the system. Study holds ProTherm entries: 16675, 16676, 16677, 16678, 16679, 16680, 16681, 16682, 16683 Extra Details: Protein stability; ligand binding; dynamic landscape; calorimetry; H/D exchange

Submission Details

ID: e3RFpKka3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:48 p.m.

Version: 1

Publication Details
Celej MS;Montich GG;Fidelio GD,Protein Sci. (2003) Protein stability induced by ligand binding correlates with changes in protein flexibility. PMID:12824495
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
4LUF 2013-07-25T00:00:00+0000 2.3 Crystal Structure of Ovine Serum Albumin
4LUH 2013-07-25T00:00:00+0000 2.2 Complex of ovine serum albumin with 3,5-diiodosalicylic acid
5ORF 2017-08-16T00:00:00+0000 2.54 Structure of ovine serum albumin in P1 space group
6HN0 2018-09-13T00:00:00+0000 2.12 Complex of Ovine Serum Albumin with diclofenac
2L7U 2010-12-23T00:00:00+0000 0 Structure of CEL-PEP-RAGE V domain complex
3V03 2011-12-07T00:00:00+0000 2.7 Crystal structure of Bovine Serum Albumin
4F5S 2012-05-13T00:00:00+0000 2.47 Crystal Structure of Bovine Serum Albumin
4JK4 2013-03-09T00:00:00+0000 2.65 Crystal Structure of Bovine Serum Albumin in complex with 3,5-diiodosalicylic acid
4OR0 2014-02-10T00:00:00+0000 2.58 Crystal Structure of Bovine Serum Albumin in complex with naproxen
6QS9 2019-02-20T00:00:00+0000 2.8 Bovine Serum Albumin in complex with Ketoprofen

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
92.4 Serum albumin P14639 ALBU_SHEEP
100.0 Serum albumin P02769 ALBU_BOVIN