Binding of low rank coal polycyclic aromatic hydrocarbons with ABTS mediated bacterial laccase: insight from molecular simulations

The polycyclic aromatic hydrocarbons (PAH) degraded by bacterial laccase with the aid of 2, 2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as mediator has been experimentally discovered by researchers, but its binding detail helping to deeply understand the enzymatic degradation process is still unclear. Here, the binding of low rank coal PAH, such as naphthalene (NAP), phenanthrene (PHE), anthracene (ANT) and pyrene (PYR), with ABTS mediated laccase were investigated with docking and molecular dynamics (MD). The results indicate that the number of hydrophobic interactions and key residues involved in laccase-PYR were the largest, and hydrophobic interaction were important to maintain their binding. The laccase was the most stable when it bound to PYR, and the water number in binding pocket maintained the minimal, which was difficult to form the hydration shell. The binding of PYR resulted in the quick folding of enzyme, and the water number in cavity increased to the largest to improve its solvent environment.