Molecular dynamics analysis of a buckyball–antibody complex

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Abstract
This is a multinanosecond molecular dynamics study of a bio–nano complex formed by a carbon nanoparticle, a buckyball C60, and a biological molecule, an antibody, with high binding affinity and specificity. In the simulation, the ball is completely desolvated by the binding site of the antibody by means of a nearly perfect shape complementarity and extensive side-chain interactions, with the exception that about 17% of the surface is persistently exposed to solvent and could be used for functional derivatization. The interactions are predominantly hydrophobic, but significant polar interactions occur as well. There exists a rich body of various π-stacking interactions. Aromatic side chains are involved in both double and triple stackings with the ball. Some ionic side chains, such as the guanidinium group of arginine, also form π-stackings with the ball. The results suggest that π-stackings are very efficient and common modes of biological recognition of π-electron-rich carbon nanoparticles. Most importantly, the results demonstrate that, in general, an ordinary protein binding site, such as that of an antibody, can readily bind to a carbon nanoparticle with high affinity and specificity through recognition modes that are common in protein–ligand recognition.