The modification of proteins through polymer conjugation is an effective synthetic mimic of naturally occurring post-translational modification. This area of research has gained much interest of the past forty years due to the ability of these bioconjugates to modulate activity and stability of various proteins while introducing new behaviors such as stimuli responsiveness and reusability. With an increasing demand for energy, several promising options that complement fossil fuels have arisen, specifically cellulosic ethanol. A significant challenge in using cellulose derives from linkages in the cellulose backbone, which cannot be hydrolyzed by yeast and many other fermenting organisms. Therefore, it is imperative to develop stable and efficient cellulase enzymes that can degrade these linkages to produce sugars that are fermentable by yeast and other microbes; as well as the ability of the enzyme to tolerate harsh conditions. Here, we describe the production of bioconjugates between polymers and a thermophilic cellulase, FnCel5a, to create an active cellulase with resistance to heat and chemical denaturation. This enzyme was conjugated with various functional polymers including cationic, anionic, and strongly and weakly hydrogen bonding polymers. The activity of FnCel5a toward a high-molecular-weight carboxymethyl cellulose substrate was enhanced by polymer conjugation and tended to confer comparable tolerance to high concentrations of dimethylformamide, with longer polymers typically enabling higher activity relative to shorter polymers. The new FnCel5a conjugates represent an advance in the production of cellulases that maintain activity at high temperatures or in the presence of denaturing organic solvents.

Polymer conjugation to enhance cellulase activity and preserve stability

2019 Spring National Meeting

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