Effects of macromolecular crowding on the structure of a protein complex: a small-angle scattering study of superoxide dismutase

Ajith Rajapaksha; Christopher B Stanley; Brian A Todd

doi:10.1016/j.bpj.2014.12.046

Effects of macromolecular crowding on the structure of a protein complex: a small-angle scattering study of superoxide dismutase

Biophys J. 2015 Feb 17;108(4):967-974. doi: 10.1016/j.bpj.2014.12.046.

Authors

Ajith Rajapaksha¹, Christopher B Stanley², Brian A Todd³

Affiliations

¹ Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana.
² Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
³ Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana. Electronic address: batodd@purdue.edu.

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.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Neutron Diffraction
Polyethylene Glycols / chemistry
Protein Binding
Protein Conformation
Scattering, Small Angle
Superoxide Dismutase / chemistry*

Substances

Polyethylene Glycols
Superoxide Dismutase