Biodegradation of anionic polyacrylamide by manganese peroxidase: docking, virtual mutation based on affinity, QM/MM calculation and molecular dynamics simulation

Manganese peroxidase (Mn P) is capable of effectively degrading anionic polyacrylamide (HPAM). However, the interaction of Mn P with HPAM at molecular level is lacking until now. Here, the HPAM model compounds, HPAM-2, HPAM-3, HPAM-4, and HPAM-5, were selected to reveal their binding mechanisms with Mn P. The results showed that the most suitable substrate for Mn P was HPAM-5, and the main reason for MnP-HPAM-5 with maximal affinity was strong hydrogen bond. LYS96 was the important key residue in all complexes, and the number of key residue was largest in MnP-HPAM-5. The optimal THR27ILE mutant may enhance the affinity of Mn P to HPAM-4. The stability of Mn P binding to HPAM-4 was the optimal. These results were helpful in designing highly efficient Mn P against HPAM to protect the ecological environment.