Molecular and Interactions Modelling of PETase and Its Variant with Different Types of Crosslinker in Enzyme Immobilization

Plastics are made from non-renewable resources and due to the tremendous production of plastics nowadays, they can lead to high levels of pollution. Biodegradation of plastic by utilizing enzymatic catalytic reaction is an environmentally friendly strategy that produce less or no negative carbon footprint.  PETase from Ideonella sakaiensis (IsPETase) is an enzyme that able to degrade polyethylene terephthalate (PET), a building block of plastic.  However, free enzyme has several limitations such as unstable in harsh conditions and lack of reusability. One of the strategies to overcome this drawback is through enzyme immobilization that able to improve the enzymatic properties. A suitable crosslinker is very important as it would determine the interactions of the enzymatic particles. Crosslinker should be chosen before performing the enzyme immobilization and this can be accomplished by molecular docking. Thus, the purpose of this research is to determine the suitability of glutaraldehyde, chitosan, dialdehyde starch (DAS) and ethylene glycol as the crosslinker for IsPETase and its variant. Three-dimensional structure of the enzymes was built and docked with different types of crosslinkers. Binding affinity and interactions between the enzymes and the crosslinkers were analyzed and it was found that chitosan has the lowest binding affinity (-7.9 kcal/mol) and the highest number of interactions. This is followed by DAS, ethylene glycol and glutaraldehyde. By using computational analysis, suitable crosslinker for IsPETase could be determine and this would a cost-effective practice in enzyme immobilization strategy.