Poster Title

Protein Engineering to Efficiently Degrade Carbohydrates for Biofuel Production

Grade Level at Time of Presentation

Sophomore

Institution

University of Kentucky

KY House District #

77

KY Senate District #

28

Department

Dept. of Molecular and Cellular Biochemistry

Abstract

Traditional fermentation of starch-rich biomass requires significant energy and resource input to degradethe starch into simple sugars like glucose for downstream processing to convert it into ethanol. Starch accumulates in plants when the excess glucose sugars produced in the presence of sunlight are joined together into chains. During the night, plants must access the glucose energy within starch to continue cellular functions. Enzymes called amylases release the glucose units from starch. However, because starch is water-insoluble, it clumps up and is difficult for the amylases to access. The Gentry lab has been investigating the enzymes plants use that enable the starch to become more accessible to degradation. These enzymes contain two regions, a binding region and an action region. The binding region attaches the enzyme to the starch while the action region modifies the starch into a more soluble form. We hypothesized that different binding regions could be appended to the action regions of the modifying enzymes in order to target and modify different carbohydrates. As proof of principle, we engineered new enzymes that would also modify starch to show that the action regions would still function with a different binding region. When comparing the activity of the original and engineered enzymes, we found that one of our engineered enzymes possessed greater activity than the original. These results allow us to expand our work to other carbohydrates such as cellulose, the most abundant carbohydrate found in nature. This project contributes to efforts in diversifying energy resources and increasing sustainable fuel sources with investigations into second-generation cellulosic biofuels that are exploring more efficient methods for breaking down cellulose into more simple sugars for fermentation.

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Protein Engineering to Efficiently Degrade Carbohydrates for Biofuel Production

Traditional fermentation of starch-rich biomass requires significant energy and resource input to degradethe starch into simple sugars like glucose for downstream processing to convert it into ethanol. Starch accumulates in plants when the excess glucose sugars produced in the presence of sunlight are joined together into chains. During the night, plants must access the glucose energy within starch to continue cellular functions. Enzymes called amylases release the glucose units from starch. However, because starch is water-insoluble, it clumps up and is difficult for the amylases to access. The Gentry lab has been investigating the enzymes plants use that enable the starch to become more accessible to degradation. These enzymes contain two regions, a binding region and an action region. The binding region attaches the enzyme to the starch while the action region modifies the starch into a more soluble form. We hypothesized that different binding regions could be appended to the action regions of the modifying enzymes in order to target and modify different carbohydrates. As proof of principle, we engineered new enzymes that would also modify starch to show that the action regions would still function with a different binding region. When comparing the activity of the original and engineered enzymes, we found that one of our engineered enzymes possessed greater activity than the original. These results allow us to expand our work to other carbohydrates such as cellulose, the most abundant carbohydrate found in nature. This project contributes to efforts in diversifying energy resources and increasing sustainable fuel sources with investigations into second-generation cellulosic biofuels that are exploring more efficient methods for breaking down cellulose into more simple sugars for fermentation.