Structural insights and functional characterization of a novel β-glucosidase derived from Thermotoga profunda

β-Glucosidase is a crucial cellulase, as its activity determines the efficiency of cellulose hydrolysis into glucose. This study addresses the functional and structural characteristics of Thermotoga profunda β-glucosidase (Tp-BGL). Tp-BGL exhibited a K_m of 0.3798 mM for p-nitrophenyl-β-d-glucopyranoside (pNPGlc) and 4.44 mM for cellobiose, with k_cat/K_m of 1211.16 and 4.18 s^-1 mM^-1, respectively. In addition, Tp-BGL showed significant pH adaptability and thermal stability, with a T_m of 85.7 °C and retaining >90 % of its activity after incubation at 80 °C for 90 min. The crystal structure of Tp-BGL was resolved at 1.95 Å resolution, and reveals a typical TIM barrel structure. Comparative structural analysis highlighted that the major distinction between Tp-BGL and the other glucosidases lies in their loop regions.