Designing materials functioning in harsh environments is vital for a range of applications. In particular, enhancing thermal stability of various enzymes is beneficial for applications ranging from food processing to deconstruction of biomass for biofuel industry. We show that conjugating lysozymes with a copolymer [poly(GMA-stat-OEGMA)] comprising glycidyl methacrylate (GMA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) dramatically increases the thermal stability of these enzymes well above 100<sup>0</sup>C. This conjugation strategy leads to the formation of cocoons around the enzymes. Using molecular dynamics simulations, we focus on understanding the underlying reasons for the observed thermal stabilization. We represent copolymer with the triads containing the same ratio of GMA to OEGMA units as in our experiments. We conjugated these triads with all the lysine residues of the enzyme, and in addition randomly placed free-floating triads within the simulation box mimicking effects of non-reacted side chains in our experiments. We focus on dynamics of the conjugate at high temperatures and on its structural stability at various copolymer concentrations. We characterize the evolution of the number of the intra-protein hydrogen bonds and the number of contacts between all the species in the system as phase separation and protein unfolding takes place. We also focus on dynamics of the secondary structures within the conjugates. Our simulations show that the water concentration in the close vicinity of the enzyme plays a defining role in maintaining its structural stability at high temperatures; we identify critical water concentration below which a robust stabilization is observed. These results are in agreement with our experimental observations showing densification of the cocoon in the close vicinity of the enzymes.

Designing highly thermostable biocatalysts

255th National Meeting (2018)

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