Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions.
We have studied a series of samples of bovine serum albumin (BSA) solutions with protein concentration, c, ranging from 2 to 500 mg/mL and ionic strength, I, from 0 to 2 M by small-angle X-ray scattering (SAXS). The scattering intensity distribution was compared to simulations using an oblate ellips...
| প্রধান লেখক: | , , , , , |
|---|---|
| বিন্যাস: | Journal article |
| ভাষা: | English |
| প্রকাশিত: |
2007
|
| _version_ | 1826273161594798080 |
|---|---|
| author | Zhang, F Skoda, M Jacobs, R Martin, R Martin, C Schreiber, F |
| author_facet | Zhang, F Skoda, M Jacobs, R Martin, R Martin, C Schreiber, F |
| author_sort | Zhang, F |
| collection | OXFORD |
| description | We have studied a series of samples of bovine serum albumin (BSA) solutions with protein concentration, c, ranging from 2 to 500 mg/mL and ionic strength, I, from 0 to 2 M by small-angle X-ray scattering (SAXS). The scattering intensity distribution was compared to simulations using an oblate ellipsoid form factor with radii of 17 x 42 x 42 A, combined with either a screened Coulomb, repulsive structure factor, SSC(q), or an attractive square-well structure factor, SSW(q). At pH = 7, BSA is negatively charged. At low ionic strength, I < 0.3 M, the total interaction exhibits a decrease of the repulsive interaction when compared to the salt-free solution, as the net surface charge is screened, and the data can be fitted by assuming an ellipsoid form factor and screened Coulomb interaction. At moderate ionic strength (0.3-0.5 M), the interaction is rather weak, and a hard-sphere structure factor has been used to simulate the data with a higher volume fraction. Upon further increase of the ionic strength (I >or= 1.0 M), the overall interaction potential was dominated by an additional attractive potential, and the data could be successfully fitted by an ellipsoid form factor and a square-well potential model. The fit parameters, well depth and well width, indicate that the attractive potential caused by a high salt concentration is weak and long-ranged. Although the long-range, attractive potential dominated the protein interaction, no gelation or precipitation was observed in any of the samples. This is explained by the increase of a short-range, repulsive interaction between protein molecules by forming a hydration layer with increasing salt concentration. The competition between long-range, attractive and short-range, repulsive interactions accounted for the stability of concentrated BSA solution at high ionic strength. |
| first_indexed | 2024-03-06T22:23:58Z |
| format | Journal article |
| id | oxford-uuid:56095f4a-3fdc-4823-a139-33ea3a26c9f9 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T22:23:58Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:56095f4a-3fdc-4823-a139-33ea3a26c9f92022-03-26T16:47:46ZProtein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:56095f4a-3fdc-4823-a139-33ea3a26c9f9EnglishSymplectic Elements at Oxford2007Zhang, FSkoda, MJacobs, RMartin, RMartin, CSchreiber, FWe have studied a series of samples of bovine serum albumin (BSA) solutions with protein concentration, c, ranging from 2 to 500 mg/mL and ionic strength, I, from 0 to 2 M by small-angle X-ray scattering (SAXS). The scattering intensity distribution was compared to simulations using an oblate ellipsoid form factor with radii of 17 x 42 x 42 A, combined with either a screened Coulomb, repulsive structure factor, SSC(q), or an attractive square-well structure factor, SSW(q). At pH = 7, BSA is negatively charged. At low ionic strength, I < 0.3 M, the total interaction exhibits a decrease of the repulsive interaction when compared to the salt-free solution, as the net surface charge is screened, and the data can be fitted by assuming an ellipsoid form factor and screened Coulomb interaction. At moderate ionic strength (0.3-0.5 M), the interaction is rather weak, and a hard-sphere structure factor has been used to simulate the data with a higher volume fraction. Upon further increase of the ionic strength (I >or= 1.0 M), the overall interaction potential was dominated by an additional attractive potential, and the data could be successfully fitted by an ellipsoid form factor and a square-well potential model. The fit parameters, well depth and well width, indicate that the attractive potential caused by a high salt concentration is weak and long-ranged. Although the long-range, attractive potential dominated the protein interaction, no gelation or precipitation was observed in any of the samples. This is explained by the increase of a short-range, repulsive interaction between protein molecules by forming a hydration layer with increasing salt concentration. The competition between long-range, attractive and short-range, repulsive interactions accounted for the stability of concentrated BSA solution at high ionic strength. |
| spellingShingle | Zhang, F Skoda, M Jacobs, R Martin, R Martin, C Schreiber, F Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title | Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title_full | Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title_fullStr | Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title_full_unstemmed | Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title_short | Protein interactions studied by SAXS: effect of ionic strength and protein concentration for BSA in aqueous solutions. |
| title_sort | protein interactions studied by saxs effect of ionic strength and protein concentration for bsa in aqueous solutions |
| work_keys_str_mv | AT zhangf proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions AT skodam proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions AT jacobsr proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions AT martinr proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions AT martinc proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions AT schreiberf proteininteractionsstudiedbysaxseffectofionicstrengthandproteinconcentrationforbsainaqueoussolutions |