tfxa (GenBank: U01242), which encoded the
mature peptide of Thermomonospora fusca TF xylanase
A (TfxA), was high-level expressed in Escherichia coli
BL21 (DE3). The recombinant xylanase, reETfxA, was
both secreted into culture medium and in the cytoplasm.
reETfxA showed high xylanase activity and was purified
to homogeneity by Ni-affinity resin (182.8 and 681.4
U mg−1 for crude and purified enzyme, respectively).
Sodium dodecyl sulphate–polyacrylamide gel electrophoresis
and Western blot analysis revealed that the molecular
mass of reETfxA was approximately 42.7 kDa. The
reETfxA was immobilized on a novel mesoporous SiO2
microsphere (MSM)-coated chitosan via covalent bonds,
which formed from Schiff base r... More
tfxa (GenBank: U01242), which encoded the
mature peptide of Thermomonospora fusca TF xylanase
A (TfxA), was high-level expressed in Escherichia coli
BL21 (DE3). The recombinant xylanase, reETfxA, was
both secreted into culture medium and in the cytoplasm.
reETfxA showed high xylanase activity and was purified
to homogeneity by Ni-affinity resin (182.8 and 681.4
U mg−1 for crude and purified enzyme, respectively).
Sodium dodecyl sulphate–polyacrylamide gel electrophoresis
and Western blot analysis revealed that the molecular
mass of reETfxA was approximately 42.7 kDa. The
reETfxA was immobilized on a novel mesoporous SiO2
microsphere (MSM)-coated chitosan via covalent bonds,
which formed from Schiff base reaction between supports
and enzyme. The binding capacity of the prepared MSMcoated
chitosan particles to reETfxA was approximately
272.6 mg g−1-particles. The optimum temperature values
of the free and immobilized reETfxA were 65 and 70°C,
respectively. Moreover, the optimum pH values of the free
and immobilized reETfxA were pH 6.0 and 5.0, respectively.
The reETfxA showed relatively high thermostability.
When treated at 70°C and pH 6.0 for 15 min, the residual
activities of free and immobilized reETfxA were 84.2 and
100.2%, respectively The results obtained from the HPLC analysis showed that immobilized reETfxA released xylooligosaccharides
from oat spelt, beechwood and birchwood
xylans, with xylotetraose, xylotriose, and xylopentaose as
the major products, respectively. Additionally, the immobilized
reETfxA could directly hydrolyze the wheat bran
insoluble xylan
