INDENBOM Andrey A.N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS (IPCE RAS)

Spoluautoři BREVNOV Vladimir
Spolupracující instituce: Moscow Institute of Physics and Technology (MIPT), Moscow, Russian Federation

Proteins are biological nanoobjects. The structure of the proteins plays a crucial role in their functioning. We have shown how SPR tecnique allows determining the shape of proteins and its changes under the influence of external conditions. Adsorption of matrix M1 protein of influenza virus on the self-assembled monolayer of mercaptohexadecanoic was studied by SPR. Acid groups on the surface of a substrate provide its negative charge similar to the charge of the lipid envelope membrane of the influenza virus. It is shown that the protein adsorbes irreversibly and formes on the surface of the substrate saturated monolayer under the action of the electrostatic attraction forces. However, the density of the monolayer depends essentially on the conditions of its formation. It was found that in a neutral medium, this protein forms monolayers of identical density at any initial concentrations of protein in solution. A different situation occurs in an acidic medium (pH below 5). Under these conditions, the protein forms more dense (thick) layers in the concentrated solutions and more rarefied (thin), but the same saturated layers, in dilute solutions. These results suggest that the protein in a neutral medium has rather symmetrical globular shape, and in an acidic medium it is oblong molecule. In concentrated solutions, the protein apparently adsorbes predominantly orthogonally to the surface, forming a dense thick coat. In dilute solutions, on the contrary, most of the molecules adsorb laterally, forming thinner layers. The proposed method can be used in the future to analyze shape of other irreversibly adsorbed proteins and nanoparticles.