Efficient immobilization of agarase using carboxyl-functionalized magnetic nanoparticles as support|
Xiao, Anfeng; Xiao, Qiong; Lin, Yan; Ni, Hui; Zhu, Yanbing & Cai, Huinong
Background: A simple and efficient strategy for agarase immobilization was developed with carboxyl-functionalized
magnetic nanoparticles (CMNPs) as support. The CMNPs and immobilized agarase (agarase-CMNPs) were
characterized by transmission electron microscopy, dynamic light scattering, vibrating sample magnetometry,
scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and zeta-potential analysis. The
hydrolyzed products were separated and detected by ESI-TOF-MS.
Results: The agarase-CMNPs exhibited a regular spherical shape with a mean diameter of 12 nm, whereas their
average size in the aqueous solution was 43.7 nm as measured by dynamic light scattering. These results
indicated that agarase-CMNPs had water swelling properties. Saturation magnetizations were 44 and 29 emu/g
for the carriers and agarase-CMNPs, respectively. Thus, the particles had superparamagnetic characteristics, and
agarase was successfully immobilized onto the supports. Agaro-oligosaccharides were prepared with agar as
substrate using agarase-CMNPs as biocatalyst. The catalytic activity of agarase-CMNPs was unchanged after six
reuses. The ESI-TOF mass spectrogram showed that the major products hydrolyzed by agarase-CMNPs after six
recycle uses were neoagarotetraose, neoagarohexaose, and neoagarooctaose. Meanwhile, the end-products after
90 min of enzymatic treatment by agarase-CMNPs were neoagarobiose and neoagarotetraose.
Conclusions: The enhanced agarase properties upon immobilization suggested that CMNPs can be effective carriers
for agarase immobilization. Agarase-CMNPs can be remarkably used in developing systems for repeated batch
production of agar-derived oligosaccharides.
Agar-derived oligosaccharides; Agaro-oligosaccharide; Dynamic light scattering; Enzyme characterization; Scanning electron microscopy; Thermogravimetric analysis; Transmission electron microscopy; Vibrating sample magnetometry; X-ray diffraction; Zeta-potential analysis