Improving special hydrolysis characterization into Talaromyces thermophilus F1208 xylanase by engineering of N-terminal extension and site-directed mutagenesis in C-terminal

Publication date: March 2017
Source:International Journal of Biological Macromolecules, Volume 96
Author(s): Qin Li, Baoguo Sun, Ke Xiong, Chao Teng, Youqiang Xu, Liangjun Li, Xiuting Li
The purpose of this study was to gain insights into the hydrolysis characteristics of xylanase in producing xylo-oligosaccharides and to improve these by protein engineering. In this study, a hybrid enzyme (T-XynFM) was created from Talaromyces thermophilus F1208 xylanase (T-Xyn) by replacement of the N-terminal extension Phe1-Pro16 with Ala1-Gln8 and substitution of amino acid Phe193 (185) with Ser in the C-terminal. The enzyme showed optimum activity at 55°C and pH 6.5. Its residual activity was more than 55% after treatment at 50°C, pH 6.5 for 12h Km values of T-XynFM for beechwood xylan, birchwood xylan, and oat-spelt xylan were 10.31, 10.03, and 8.90mgmL⁻¹, respectively. The enzyme displayed special hydrolysis characteristics: almost no xylose was produced on using xylotriose (X3), xylotetraose (X4), and xylopentaose as substrates. Moreover, over 60% X4 existed in hydrolyzed products of X3, indicating that T-XynFM possesses formidable transglycosylation properties.



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