Simulation Study of Polyethylene Terephthalate Hydrolase Adsorption on Self-Assembled Monolayers

Area of Science:

• Biocatalysis
• Protein Immobilization
• Computational Chemistry

Background:

• Polyethylene terephthalate (PET) hydrolase (IsPETase) from Ideonella sakaiensis offers mild PET biodegradation but suffers from poor thermal stability.
• Efficient immobilization and controlled orientation of IsPETase on solid substrates are crucial for enhancing its industrial applicability.

Purpose of the Study:

• To elucidate the adsorption mechanism, orientation, and conformational changes of IsPETase on charged self-assembled monolayers (SAMs).
• To investigate the influence of surface charge density (SCD) on IsPETase adsorption and catalytic site accessibility.

Main Methods:

• Combined parallel tempering Monte Carlo (PTMC) and all-atom molecular dynamics (MD) simulations were employed.
• IsPETase adsorption on COOH-SAM and NH2-SAM with varying SCDs was analyzed at the atomistic level.

Main Results:

• Protein adsorption orientation is governed by both attractive and repulsive interactions.
• IsPETase adopts an "end-on" orientation on COOH-SAM, exposing the catalytic triplet to the solution.
• A larger catalytic active center entrance was observed on COOH-SAM surfaces with low SCD.

Conclusions:

• This study provides atomistic insights into the controlled orientation and conformational dynamics of IsPETase on charged surfaces.
• Findings support the rational design of immobilization substrates to enhance IsPETase performance in PET biodegradation.