title: Effects of macromolecular crowding on the structure of a protein complex: a small-angle scattering study of superoxide dismutase.
abstract: Macromolecular crowding can alter the structure and function of biological macromolecules. We used small-angle scattering to measure the effects of macromolecular crowding on the size of a protein complex, SOD (superoxide dismutase). Crowding was induced using 400 MW PEG (polyethylene glycol),TEG (triethylene glycol), α-MG (methyl-α-glucoside), and TMAO (trimethylamine n-oxide). Parallel small-angle neutron scattering and small-angle x-ray scattering allowed us to unambiguously attribute apparent changes in radius of gyration to changes in the structure of SOD. For a 40% PEG solution, we find that the volume of SOD was reduced by 9%. Considering the osmotic pressure due to PEG, this deformation corresponds to a highly compressible structure. Small-angle x-ray scattering done in the presence of TEG suggests that for further deformation-beyond a 9% decrease in volume-the resistance to deformation may increase dramatically.
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana.
authors.forename: Ajith
authors.initials: A
authors.lastname: Rajapaksha
authors.affiliation: Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Stanley
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana. Electronic address: batodd@purdue.edu.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Todd
mesh_terms: D033363:Neutron Diffraction; D011092:Polyethylene Glycols / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D053838:Scattering, Small Angle; D013482:Superoxide Dismutase / Q000737:chemistry*
chemical_list: D011092:Polyethylene Glycols; D013482:Superoxide Dismutase