Thermostable Sites and Catalytic Characterization of Xylanase XYNB of Aspergillus niger SCTCC 400264

Abstract

In order to improve the expression of heat-resistant xylanase XYNB from Aspergillus niger SCTCC 400264, XynB has been cloned into Pichia pastoris secretary vector pPIC9K. The XynB production of recombinant P. pastoris was four times as E. coli, the Vmax and specific activity of XynB reached 2,547.7 μmol/mg and 4,757 U/mg, respectively. And the XynB still had 74% residual enzyme activity after 30 min-heat treatment at 80°C. The van der Waals force analysis in XYNB (ACN89393 and AAS67299), there is one more oxygen radicals in AAS67299 in their catalytic site, indicating that the local cavity is much more free, and it is more optimal for substrate binding, affinity reaction, and proton transfer etc, and eventually increasing enzyme activity. The H-bonds analysis of XYNB indicated that there are two more H-bonds in 33rd Ser of XYNB (AAS67299) than 33rd Ala(ACN89393 ), two H-bonds between Ser70 and Asp67.

High-level expression and characterization of Aspergillus niger ATCC 1015 xylanase B in Komagataella phaffii

“…In the present study, the optimal temperature of xylanase B was 55°C, which is higher than that of most of the xylanases from other Aspergillus strains, such as Aspergillus usamii E001 xynI, A. sulphureus xylanase B, A. niger CGMCC1067 xynB, and A. niger IA-001 (Table 1). Only A. niger SCTCC 400264 xylanase showed the same optimal temperature and pH as those of xylanase B obtained in the present study [25]. The activity of xylanase B at 60°C was only 0.04% lower than that at 55°C.…”

Mutagenesis of N-terminal residues confer thermostability on a Penicillium janthinellum MA21601 xylanase

“…Thermostability is a desirable property of xylanases for industrial applications [23], especially for the mesophilic xylanases like PjxA which have high specific activity under acidic condition. Enhancing thermal stability is the usual requisite for enzymes to be successfully applied in the animal feed industry [24]. Previous studies have proposed that the heat-mediated unfolding of GH11 xylanases initiates from the N-terminal region [21, 25].…”

C-Terminal proline-rich sequence broadens the optimal temperature and pH ranges of recombinant xylanase from Geobacillus thermodenitrificans C5

“…4), which is far better than that of its wild type xylanase. This increase in thermal stability is far better than most of the bacterial xylanases that are previously reported [36][37][38][39].…”