Covalent Immobilization of Bacillus licheniformis γ-Glutamyl Transpeptidase on Aldehyde-Functionalized Magnetic Nanoparticles

Abstract

This work presents the synthesis and use of surface-modified iron oxide nanoparticles for the covalent immobilization of Bacillus licheniformis γ-glutamyl transpeptidase (BlGGT). Magnetic nanoparticles were prepared by an alkaline solution of divalent and trivalent iron ions, and they were subsequently treated with 3-aminopropyltriethoxysilane (APES) to obtain the aminosilane-coated nanoparticles. The functional group on the particle surface and the amino group of BlGGT was then cross-linked using glutaraldehyde as the coupling reagent. The loading capacity of the prepared nanoparticles for BlGGT was 34.2 mg/g support, corresponding to 52.4% recovery of the initial activity. Monographs of transmission electron microscopy revealed that the synthesized nanoparticles had a mean diameter of 15.1 ± 3.7 nm, and the covalent cross-linking of the enzyme did not significantly change their particle size. Fourier transform infrared spectroscopy confirmed the immobilization of BlGGT on the magnetic nanoparticles. The chemical and kinetic behaviors of immobilized BlGGT are mostly consistent with those of the free enzyme. The immobilized enzyme could be recycled ten times with 36.2% retention of the initial activity and had a comparable stability respective to free enzyme during the storage period of 30 days. Collectively, the straightforward synthesis of aldehyde-functionalized nanoparticles and the efficiency of enzyme immobilization offer wide perspectives for the practical use of surface-bound BlGGT.

Knockout of pgdS and ggt gene changes poly-γ-glutamic acid production in Bacillus licheniformis RK14-46

“…With respect to γ-PGA production, overexpression of the pgdS gene in B. licheniformis WX-02 unexpectedly increased the γ-PGA production by 54% and decreased the molecular masses of γ-PGA molecules (Tian et al 2014). GGT of B. licheniformis strain has been well characterized in heterogeneous expression systems (Lin et al 2006) and has been applied in enzymatic reactions (Chen et al 2013). However, the effects of ggt overexpression or disruption on γ-PGA production of B. licheniformis have not been described previously.…”

Immobilization of feruloyl esterases on magnetic nanoparticles and its potential in production of ferulic acid

“…A similar study conducted on immobilized lipase by various MNPs (naked and modified Fe 3 O 4 ) demonstrated that the amount of immobilized lipase increased with increasing enzyme concentration, but the activity of immobilized enzyme was found reduced at the same condition (31). It probably due to the multiple layers of enzyme molecules were formed on the surface of MNPs at high enzyme loading, which might block the active sites of the enzyme and caused the diffusion limitation of the substrate (32).…”

Bacterial γ-glutamyltranspeptidase: Food and medicinal applications

“…Currently, immobilization of an enzyme is one of the widely performed methods. GGTs from Bacillus species have also been immobilized [40][41][42] , but the authors provide data of the total enzymatic activity, which implies both transpeptidation and hydrolysis activities. Unlike E. coli GGT, GGTs from Bacillus species have pH optima of both activities at basic pH.…”