Structural peculiarities of lysozyme-graphene oxide adsorption complexes

Lysozyme adsorption complexes with graphene oxide (GO) and reduced GO were studied by means of radiotracer method using tritium as a label. The experiment includes adsorption study, with amount and enzymatic activity control, and revealing structural peculiarities of lysozyme adsorbed on graphene oxide surface by analysis of tritium distribution in the amino acid residues after the bombardment with atomic tritium. Experimental and molecular docking results suggested that lysozyme adsorbs directly on GO by formation of bonds between GO surface and Cys6 and Arg128 that contribute to formation conformation, in which aromatic residues forms pi-pi bonds with GO surface, and positively charged amino acid residues bind with O-containing groups of GO via electrostatic attraction. In the follow-up layers lysozyme molecules interact with each other that result in changes and adsorbed lysozyme molecules resulting in changes in protein structure. Such changes are not critically significant but lead to increase of availability of an active site of the enzyme for binding with a substrate after the desorption from the multilayer.