Sung Ok Han

D-Sorbose, a health-promoting rare sugar with growing demand in food and pharmaceutical applications, faces commercial production challenges due to its low conversion efficiency and thermodynamic equilibrium constraints in conventional enzymatic processes. In this study, a Catcher-Tag-scaffolded dual-enzyme cascade was developed for the conversion of d-galactose to d-sorbose, with d-tagatose as an intermediate. Lactobacillus fermentum l-arabinose isomerase (LfAraA) and Pseudomonas cichorii d-tagatose 3-epimerase (PcDTEase) were assembled onto SpyCatcher/DogCatcher scaffolds to enhance enzyme proximity and continuous cascade reactions. Compared to free enzymes, the scaffolded complex increased d-sorbose yield by 21%, exhibiting lower K_m and higher k_cat/K_m, demonstrating improved substrate affinity and catalytic efficiency. These results establish scaffold-guided enzyme assembly as a robust and scalable platform for rare sugar biosynthesis with strong industrial potential.

Red algae, a type of marine biomass, have garnered attention due to their significant economic potential. Agarose, the gelling component of agar, is composed of d-galactose and 3,6-anhydro-l-galactose. In this study, an enzyme-based multienzyme complex was designed to convert agarose into monosaccharides. Briefly, endo-type β-agarase and neoagarobiose hydrolase were employed, and the multienzyme complex was assembled using Catcher-Tag interactions, which facilitated efficient multienzymatic cascade reactions. Exo-type β-agarase was incorporated during the enzymatic process to enhance activity. Based on the DNS assay, a 1.78-fold increase in degradation efficiency was obtained compared to that with individual enzymes. Overall, this study proposes a promising eco-friendly and efficient enzymatic approach for producing high-value monosaccharides from red algae.

Bioplastics offer eco-friendly alternatives to conventional plastics. This study aimed to expand the application scope of bioplastics by developing a functional material with enhanced conductivity. We recombined the SpyCatcher-SpyTag system from Streptococcus pyogenes with leghemoglobin from Glycine max to generate SpyCatcher-GmLegC₂-SpyTag, SpyCatcher-GmLegC₂-SpyCatcher, and SpyTag-GmLegC₂-SpyTag proteins, which assembled into a conductive polymer. This polymer exhibited electrical conductivity 2.5 times higher than free hemin in aqueous solution when mixed with hemin. For improved stability, SpyCatcher-GmLegC₂ was fused with a carbohydrate-binding module from Clostridium cellulovorans and integrated into bacterial cellulose scaffolds. The resulting composite showed a 141-fold increase in conductivity compared to free hemin and exhibited uniform, stable performance. This eco-friendly conductive bioplastic demonstrates strong potential for applications in wearable sensors, electronic devices, and sustainable conductive materials.