Journal article
Revealing the Dimeric Crystal and Solution Structure of β-Lactoglobulin at pH 4 and Its pH and Salt Dependent Monomer–Dimer Equilibrium
Department of Biotechnology and Biomedicine, Technical University of Denmark1
Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark2
Department of Micro- and Nanotechnology, Technical University of Denmark3
University of Copenhagen4
Amphiphilic Polymers in Biological Sensing, Department of Micro- and Nanotechnology, Technical University of Denmark5
Department of Chemistry, Technical University of Denmark6
X-ray Crystallography, Department of Chemistry, Technical University of Denmark7
The dimeric structure of bovine β-lactoglobulin A (BLGA) at pH 4.0 was solved to 2.0 Å resolution. Fitting the BLGA pH 4.0 structure to SAXS data at low ionic strength (goodness of fit R-factor = 3.6%) verified the dimeric state in solution. Analysis of the monomer–dimer equilibrium at varying pH and ionic strength by SAXS and scattering modeling showed that BLGA is dimeric at pH 3.0 and 4.0, shifting toward a monomer at pH 2.2, 2.6, and 7.0 yielding monomer/dimer ratios of 80/20%, 50/50%, and 25/75%, respectively.
BLGA remained a dimer at pH 3.0 and 4.0 in 50–150 mM NaCl, whereas the electrostatic shielding raised the dimer content at pH 2.2, 2.6, and 7.0, i.e., below and above the pI. Overall, the findings provide new insights into the molecular characteristics of BLGA relevant for dairy product formulations and for various biotechnological and pharmaceutical applications.
| Language: | English |
|---|---|
| Publisher: | American Chemical Society |
| Year: | 2018 |
| Pages: | 2905-2912 |
| ISSN: | 15264602 and 15257797 |
| Types: | Journal article |
| DOI: | 10.1021/acs.biomac.8b00471 |
| ORCIDs: | 0000-0003-2658-414X , Khan, Sanaullah , Harris, Pernille , Almdal, Kristoffer and Svensson, Birte |
