NSF Award
2306137
Non-technical summary/abstract<br/><br/>Contemporary life and society depend heavily on energy and materials sources. Certain sources are non-sustainable, meaning that they cannot be replenished quickly once consumed, while others are sustainable and can be regenerated. Unfortunately, non-sustainable sources are running out rapidly; thus, the nation could benefit both environmentally and economically from an improved use of sustainable sources. Plants are promising sustainable sources, which offer fuels, materials, and nutrients. Yet, these valuable components cannot be easily taken out from plants, because they are trapped in plant skins. Typical plant skins are composed of complex species, such as i) an intense network of numerous, cross-linked large molecules, known as cellulose, ii) a bunch of small molecules known as lipids which line up and assemble into plant cell membranes, and iii) glycoproteins, molecules formed by sugar-like molecules connected with proteins. These species build up a hard protection layer to plants, which cannot be broken down easily. This project will develop special biomaterials to break down such a protection layer. A series of enzymes, special proteins which speed up the breaking-down of cellulose, lipids, and glycoproteins, will be placed in the scaffolds and gaps of a solid crystal, known as Ca-MOM. These enzymes will cooperate to degrade the protection layer of plants without generating adverse by-products. The Ca-MOM crystal will stabilize and help re-collect the enzymes, making them reusable. Meanwhile, the positions of the enzymes in the crystal scaffolds will also be probed to understand the performance of the enzymes in the developed biomaterials. These efforts will not only produce biomaterials to efficiently and sustainably break down plant skins to allow for the extraction of valuable energy resources and materials but also understand how enzymes function in these biomaterials. The demonstrated strategy will also improve the progress of science because it can be adapted to breaking down of other natural sources which contain valuable components and require multiple enzymes to cooperate. The research efforts will be bridged with an educational plan to bring research opportunities to local underrepresented groups by involving them in green chemistry research. This principle investigator will also develop an educational program called Green Chemistry- Green Planet in order to introduce the green chemistry concept to local elementary students through established programs such as the North Dakota (ND) 4-H and Operation Military Kids programs in ND.<br/><br/><br/>Technical summary/abstract<br/><br/>Plants are sustainable sources of energy and materials, yet the valuable components are protected by plant cell walls. The challenges to break down these cell walls are the difficulty in degrading the intense cellulose network, the major cause of cell wall stiffness, and complexities due to other components such as lipids and glycoproteins, which also enhance viscosity and stiffness. Using cellulases and accessory enzymes to degrade cellulose and other components is the green choice of plant biomass degradation due to their specificity and biocompatibility, yet the challenge is the need of multiple enzymes including proteases which damage the partner enzymes. This project will overcome this challenge by immobilizing three celluases, a lipase, and a protease on Metal-Organic Materials (MOM) via enzyme-MOM co-crystallization. In the resultant co-crystals, each enzyme is partially exposed to the reaction medium for substrate contact while partially buried under MOM surfaces for enzyme protection to reduce proteolytic damage. The developed biocatalysts will be demonstrated on the degradation of a model plant biomass, followed by probing the structure-property relationship of the resultant multi-enzyme/MOM biocatalysts differing in MOM ligands using Electron Paramagnetic Resonance spectroscopy. The hypotheses are 1) simultaneous immobilization of 5 enzymes enhances the cost efficiency of and accelerate plant biomass degradation with reduced proteolytic damage and 2) the biocatalytic performance of the developed biocatalysts depends on the structural basis of enzyme exposure on MOM surfaces and MOM ligands. These hypotheses will be tested through three objectives: 1) develop a 5-in-1/Ca-BDC biocatalyst for the rapid biodegradation of plant biomass, 2) determine the structural basis of the 5-in-1/Ca-BDC biocatalyst, and 3) establish the structure-property relationship of the 5-in-1/Ca-MOMs the biocatalytic performance of the developed biocatalysts. The educational plan of this project will provide opportunities for averagely 1 Native American student, 2 undergraduate students, and 1 local high school student per year to participate in green chemistry research. In addition, an educational program called Green Chemistry - Green Planet will be developed to enhance the science knowledge of numerous K-12 students via the North Dakota (ND) 4-H system and the Operation Military Kids program in ND.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
