Molecular Understanding of Laccase Adsorption on Charged Self-Assembled Monolayers

Controlling the orientation of laccase on electrodes is crucial for the achievement of fast direct electron transfer. It is important to find a short pathway between the T1 copper site of laccase and a substrate during the laccase immobilization. In this work, we studied the adsorption orientation and conformation of Trametes versicolor laccase (TvL) on two kinds of charged self-assembled monolayers (SAMs), including NH₂-SAM and COOH-SAM, by parallel tempering Monte Carlo and all-atom molecular dynamics simulations. TvL adsorbs on positively and negatively charged surface with "end-on" and "lying" orientation, respectively. On the positively charged surface, T1 copper site of TvL is closer to the surface. The orientation of TvL on positively charged surface is narrower than that on negatively charged surface. Thus, the positively charged surface is more conducive to the immobilization of TvL. The conformational changes of TvL on the charged surfaces are analyzed by RMSD, superimposed structures, dipole moment, gyration radius, and eccentricity. Results show that native structures of TvL are well preserved when it adsorbs on the charged surfaces. This work provides atomistic insight into the mechanism of TvL adsorption on charged surface and is helpful for the design and development of laccase-based electrodes.