Structure-Function Relationships of Enzymes Involved in Starch Modification

• Main Author: Wang, Yu
• Format: Book
• Language: English
• Published: Technical University of Denmark 2023
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: https://orbit.dtu.dk/en/publications/0078958f-6773-4918-943d-2366450072d1; https://backend.orbit.dtu.dk/ws/files/353376624/PhD_thesis_Yu_Wang.pdf

Starch, a sustainable and abundant energy storage source found in human food and animal feed, plays a crucial role in diverse applications such as biomaterials, biorefineries, and biomass feedstocks for fuel energy. To enhance its properties, starch can be subjected to enzymatic, chemical, or physical treatments through structural engineering. Enzyme treatment using starch-active enzymes is an environmentally friendly and attractive approach, improving thermal properties, digestion resistance, and complexation capacity. Enhancing catalytic efficiency of these enzymes can be achieved through mutations or constructing starch binding domain (SBD) fusions, which increase the affinity of the enzymes for the substrates and consequently improve their catalytic efficiency. The thesis is divided into 5 chapters. Chapter 1 is the Introduction, which starts by an overview of the multi-level structure of starch granules. Additionally, it delves into the realm of carbohydrate active enzymes (CAZymes), with a particular emphasis on the enzymes that were studied in this thesis. It is also explored how CAZymes find application in the modification of starch. Furthermore, it is delved into the understanding of SBDs, in terms both of their structural characteristics and functional roles, along with their innovative application through SBD fusions. As the essence of this thesis, we introduce the concept of interfacial catalysis and kinetics of starch granules, and shed light on its significance. To conclude, a comprehensive overview of the fundamental materials, enzymes, and methodologies in this thesis are provided. Chapter 2 is the Result and divided into 3 subchapters. Subchapter 2.1 comprises 2 papers ( Paper 1 and Paper 2 ). Paper 1 focused on the impact of SBDs on the interfacial catalysis on granular starches by C-terminally fusing an SBD from either Aspergillus niger glucoamylase (SBD GA ) or Arabidopsis thaliana glucan, water dikinase 3 (SBD GWD3 ) to a psychrophilic α-amylase, AHA, from the Antarctic bacterium ...