Magnetic Cross-Linked Enzyme Aggregates of a Transpeptidase-Specialized Variant (N450D) of Bacillus licheniformis ?-Glutamyl Transpeptidase: An Efficient and Stable Biocatalyst for l-Theanine Synthesis

?-Glutamyl transpeptidase (GGT) catalyzes the transfer of glutathione’s ?-glutamyl group and related amides to water, amino acids or peptides, utilizes a conserved Thr residue process its own polypeptide chain into large small subunit that then assemble produce catalytically competent enzyme. In this study, magnetic cross-linked enzyme aggregates (mCLEAs) transpeptidase-specialized variant (N450D) Bacillus licheniformis GGT were successfully prepared with optimized parameters viz.1.25:1 (v/v) isopropanol N450D (0.3 mg/mL) ratio/0.02:1 (w/w) 3-aminopropyl triethoxysilane (APTES)-coated nanoparticle ratio/20 mM glutaraldehyde. The nanoparticles immobilized (N450D-mCLEAs) characterized by X-ray diffraction (XRD) Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscope integrated energy dispersive spectroscopy (FESEM/EDS), superparamagnetic analysis. As compared free enzyme, N450D-mCLEAs displayed significantly higher heat resistance at temperatures 55 60 °C, had greater stability over storage period one month. could also be reused for 10 consecutive biocatalytic cycles no significant reduction in percent yield l-theanine. Conclusively, immobilization strategy surely provides meaningful glance developing N450D-mediated biocatalysis production physiologically important compounds.