In-silico structural and functional evaluation of laccase enzymes for binding and degradation of Polyethylene Terephthalate (PET)

Abstract

The invention of plastic materials made our lives increasingly convenient through production of many dependable and convenient materials. However, the problem of decomposing these materials has led to a surge of plastic waste, causing environmental and health risk. Many of the use once and other plastic materials commonly used are polymers of Polyethylene Terephthalate (PET) owing to their durability, thermal stability and relatively low prices thus their waste volume is overwhelming. Currently, landfilling, recycling, and incineration treatment approaches are either insufficient or not environmentally friendly necessitating the need for a more eco-friendly and sustainable biodegradation approaches. Biodegradation which is the breaking down chemical compounds by microorganisms or their enzymes is a more effective and operative method for resolving the global plastic waste problem. Plastic biodegradation occurs in four successive steps: biodeterioration, depolymerization, assimilation, and mineralization. Plastic biodegradation by these microorganisms includes different enzymatic reactions, converting synthetic plastics into simple mineral materials. These enzymes are part of metabolic pathways that use these polymers as primary substrates. The intellectual design of enzymes for plastic degradation and advancing their biodegradation efficacy is on the rise and microbial enzymes like PETases, Lipases among others have been reported to bind and degrade PET. Multicopper oxidases particularly Laccases known for lignin degradation in fungi and cuticle sclerotization in insects have a broad substrate range, including diphenols, aromatic amines, polyphenols, and methoxy-substituted phenols and have been utilized in industrial applications such as wastewater treatment, paper bleaching, textile color degradation, and lignin modification. However, their PET-degradation potential has not been studied. In here, I assessed the PET binding and degradation potential of a set of 10 laccases of which 6 were from bacteria, 3 from fungi and 1 from archaea through in silico approaches. Molecular docking-based evaluation of the binding efficiencies of all the laccases with polyethylene terephthalate (PET), revealed that the bacterial laccase from Thermus thermophilus had the lowest binding energy of −7.1kcal/mol suggesting that it might be particularly well-suited for binding and potentially degrading PET.