TY  - JOUR
AU  - Zhang, F.
AU  - Roosen-Runge, F.
AU  - Skoda, M.W.A.
AU  - Jacobs, R.M.J.
AU  - Wolf, M.
AU  - Callow, P.
AU  - Frielinghaus, H.
AU  - Pipich, V.
AU  - Prévost, S.
AU  - Schreiber, F.
TI  - Hydration and interactions in protein solutions containing concentrated electrolytes studied by small-angle scattering
JO  - Physical Chemistry Chemical Physics
VL  - 14
SN  - 1463-9076
CY  - Cambridge
PB  - RSC Publ.
M1  - PreJuSER-19773
SP  - 2483 - 2493
PY  - 2012
N1  - We gratefully acknowledge financial support from Deutsche Forschungsgemeinschaft (DFG) and the beam time allocation from ESRF, ILL, JCNS and Helmholtz-Center Berlin (BENSC). The beam time on V4 at the Helmholtz Zentrum Berlin has been supported by the European Commission under the 6th Framework Program through the Key Action: Strengthening the European Research Area, Research Infrastructures. Contract No. RII3-CT-2003-505925 (NMI3).
AB  - During protein crystallization and purification, proteins are commonly found in concentrated salt solutions. The exact interplay of the hydration shell, the salt ions, and protein-protein interactions under these conditions is far from being understood on a fundamental level, despite the obvious practical relevance. We have studied a model globular protein (bovine serum albumin, BSA) in concentrated salt solutions by small-angle neutron scattering (SANS). The data are also compared to previous studies using SAXS. The SANS results for dilute protein solutions give an averaged volume of BSA of 91,700 Å(3), which is about 37% smaller than that determined by SAXS. The difference in volume corresponds to the contribution of a hydration shell with a hydration level of 0.30 g g(-1) protein. The forward intensity I(0) determined from Guinier analysis is used to determine the second virial coefficient, A(2), which describes the overall protein interactions in solution. It is found that A(2) follows the reverse order of the Hofmeister series, i.e. (NH(4))(2)SO(4) < Na(2)SO(4) < NaOAc < NaCl < NaNO(3) < NaSCN. The dimensionless second virial coefficient B(2), corrected for the particle volume and molecular weight, has been calculated using different approaches, and shows that B(2) with corrections for hydration and the non-spherical shape of the protein describes the interactions better than those determined from the bare protein. SANS data are further analyzed in the full q-range using liquid theoretical approaches, which gives results consistent with the A(2) analysis and the experimental structure factor.
KW  - Animals
KW  - Cattle
KW  - Electrolytes: chemistry
KW  - Neutron Diffraction
KW  - Osmolar Concentration
KW  - Protein Interaction Mapping
KW  - Salts: chemistry
KW  - Scattering, Small Angle
KW  - Serum Albumin, Bovine: chemistry
KW  - X-Ray Diffraction
KW  - Electrolytes (NLM Chemicals)
KW  - Salts (NLM Chemicals)
KW  - Serum Albumin, Bovine (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:22249363
UR  - <Go to ISI:>//WOS:000299505400046
DO  - DOI:10.1039/c2cp23460b
UR  - https://juser.fz-juelich.de/record/19773
ER  -