An In Silico Approach to Enzymatic Synthesis of Fucooligosaccharides Using ?-l-Fucosidase from Thermotoga maritima

Fucooligosaccharides comprise the primary group of human milk oligosaccharides. Due to their beneficial properties, a series of synthetic methods have been proposed to obtain them. Enzymatic methods show great promise, and ?-l-fucosidase from Thermotoga maritima has emerged as a powerful catalyst for their production. Nonetheless, the enzyme?s limited substrate scope has delayed its wider application. The present work aims to compare the relative reactivity of fucose, pNP-fucose, and ethyl-fucose, while also exploring the molecular interactions of these fucosyl-donors with the enzyme through a combination DFT and docking analysis. The HOMO-LUMO band gaps range from ?7.14571 to ?4.24429 eV, with ?/?-pNP-fucose and ?-fucose being the three most reactive compounds. Moderate association energies between ?6.4 to ?5.5 kcalmol?1 were found in the docking analysis, with ?-pNP-fucose and both anomers of ethyl-fucose demonstrating the poorest affinity. In the case of ?/?-lactose affinity to the ?-fucose/enzyme complex, no significant differences were shown. We conclude that the best fucosyl-donors for transfucosylation are those that maintain an enzyme affinity and reactivity similar to pNP-fucose.