Interactions of carbon nanotubes and/or graphene with manganese peroxidase during biodegradation of endocrine disruptors and triclosan

Abstract

Molecular-level biodegradation processes of bisphenol A (BPA), nonylphenol (NP) and triclosan (TCS) mediated by manganese peroxidase (MnP) were investigated with and without single-walled carbon nanotube (SWCNT) and/or graphene (GRA). Although the incorporation of SWCNT, GRA or their combination (SWCNT+GRA) did not break up the complexes composed of manganese peroxidase (MnP) and these substrates, they had different effects on the native contacts between the substrates and MnP. GRA tended to decrease the overall stability of the binding between MnP and its substrates. SWCNT or SWCNT+GRA generally had a minor impact on the mean binding energy between MnP and its substrates. We detected some sensitive residues from MnP that were dramatically disturbed by the GRA, SWCNT or SWCNT+GRA. Nanomaterials changed the number and behavior of water molecules adjacent to both MnP and its substrates, which was not due to the destruction of H-bond network formed by sensitive regions and water molecules. The present results are useful for understanding the molecular basis of pollutant biodegradation affected by the nanomaterials in the environment, and are also helpful in assessing the risks of these materials to the environment.