The 11th International Conference on Agricultural and Biological Sciences (ABS 2025)

Abstract: Isomaltulose is a novel natural sweetener, possessing advantages such as low calorie content, high stability, and no adverse impacts on human health. It has been extensively applied in multiple domains like medicine and food. The enzymatic biosynthesis of isomaltulose features a high conversion rate and conforms to the requirements of green and environmental protection. Sucrose isomerase (SI) is widely used for the production of isomaltulose. By immobilizing SI, it can improve the industrial application problems such as poor stability, easy inactivation and difficult to recycle in practical application. In this study, three types of cross-linked enzyme aggregates (CLEAs) were acquired through systematic optimization of the concentrations of precipitant, cross-linking agent, and protectant. The thermal stability, pH tolerance, and storage stability of the three CLEAs preparations surpassed those of free enzymes and demonstrated good reusability. After 10 cycles of utilization, the residual activity of the three CLEAs samples remained above 61%, and CLEAS-BSA was capable of maintaining 91.7% of the initial activity. With sucrose and sugarcane juice as substrates, the sucrose conversion of CLEAs-BSA was 88.4% and 81.2%, respectively. Thereafter, SI was immobilized in combination with silica ball adsorption and cross-linked enzyme aggregates. The immobilized enzyme exhibited excellent thermal stability, pH stability, and operational stability. After the immobilized enzyme was reused for 15 times, the recovery rate of enzyme activity still exceeded 77%. Additionally, a novel affinity peptide orientation and photo-crosslinking immobilization approach was put forward. Firstly, a fixed region distant from the active site of SI was chosen by molecular simulation technology. On this basis, a short peptide VG with high affinity to this region was rationally designed. Subsequently, a photosensitive cross-linked group is introduced at the C-terminal of the short peptide. The affinity between the ligand and the target protein was verified through molecular dynamics simulation. Then, SI was fixed on the surface of epoxy resin (EP) by the optical crosslinking method to obtain the directional photo-crosslinking enzyme. The directionally immobilized enzyme demonstrated remarkable enhancement in recycling and heat resistance. Moreover, hv-EP-VG-SI retained over 90% and more than 50% of the original activity after 11 cycles. The above research has laid a solid foundation for the green manufacture of isomaltulose and also provided an innovative concept for the development of a new oriented immobilized enzyme technology.

Biography: Dr. Fufeng Liu, Tianjin distinguished Professor, Hong Kong scholar. He received his Ph. D. degree of Biochemical Engineering at Tianjin University in 2008 and then started his teaching and research career in Tianjin University and became an associate professor in 2011. He is a postdoctoral fellow under the “Hong Kong Scholars program” at the Hong Kong Polytechnic University from March 2013 to May 2015. From 2016, he has been a full professor of College of Biotechnology at Tianjin University of Science & Technology. In recent years, he integrates molecular simulations, theoretical models, biochemical and biophysical experiments to conduct fundamental research on the structure and function of proteins. His research interests include molecular dynamics simulations of the conformational transition and aggregation of amyloid protein associated human disease, rational design of enzyme molecules and multi-scale modeling of biological and material systems. His work has produced more than 140 research papers published in peer-reviewed international journals. He is now an academic editor of both foods and a member of the editorial board of Aging & Disease.