Diisobutylene Maleic Acid Copolymer (DIBMA) Lipid Particle: A “stealth” Membrane Mimetic for Neutron Scattering

Diisobutylene maleic acid (DIBMA) has been shown to solubilize and purify membrane proteins from a native lipid bilayer into nanodiscs without the need for a detergent. To explore DIBMA lipid particles as a suitable membrane mimetic system for neutron scattering studies of membrane proteins, we measured and determined the contrast matching point of DIBMA to be ~12% (v/v) D2O—similar to that of most protiated lipid molecules, but distinct from that of regular protiated proteins, providing a natural contrast for separating neutron scattering signals. Using SANS contrast variation, we demonstrated that the scattering from the whole lipid particle can be annihilated. Further, the lipid part of the particle shows a well-defined discoidal shape with DIBMA contrast matched. These results demonstrate that the DIBMA lipid particle is an outstanding “stealth” membrane mimetic for membrane proteins.