SH3-like domains from Leuconostoc citreum ABK-1 alternansucrase enables efficient enzyme immobilization

Enzyme immobilization is generally used to improve enzyme stability and reusability for industrial applications. In this study, a novel non-covalent immobilization strategy was developed using the SH3-like domains of alternansucrase from Leuconostoc citreum ABK-1 (LcAlts). SH3-like domains contain hydrophobic surface, suggesting its ability to interact with hydrophobic materials. Based on this property, LcAlts was successfully immobilized onto Phenyl Sepharose™ beads through hydrophobic interactions without the addition of anti-chaotropic salts. The immobilized enzyme exhibited strong binding stability under optimal conditions (pH 5-7 and ≤ 30 °C). Also, immobilization broadened the operational pH range and enhanced stability under acidic and thermal conditions, although a slight reduction in catalytic efficiency was observed. Importantly, the immobilized enzyme retained a similar glucooligosaccharide (GOS) product profile to that of the free enzyme. In addition, the SH3-like domains were successfully applied to immobilize a heterologous protein, demonstrating its versatility as an affinity tag. This study provides a simple and effective immobilization strategy that improves enzyme robustness while enabling easy recovery and reuse of the support material, supporting more sustainable and cost-efficient biocatalysis.