AUTHOR=Kumar Anurag , Li Jinglin , Kondaveeti Sanath , Singh Bakul , Shanmugam Ramasamy , Kalia Vipin Chandra , Kim In-Won , Lee Jung-Kul 

TITLE=Characterization of a xylitol dehydrogenase from Aspergillus flavus and its application in l-xylulose production

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.1001726

DOI=10.3389/fbioe.2022.1001726

ISSN=2296-4185

ABSTRACT=<p>An NAD<sup>+</sup>-dependent xylitol dehydrogenase from <italic>A. flavus</italic> (AfXDH) was cloned and successfully expressed in <italic>Escherichia coli</italic>. AfXDH gene sequence revealed an open reading frame of 1,110 bp, encoding a polypeptide of 369 amino acids with a calculated molecular mass of 38,893 Da. Among various polyols, sorbitol and xylitol were preferred substrates of AfXDH with K<sub>m</sub> values of 16.2 and 16.9 mM, respectively. AfXDH showed the highest activity in Tris-glycine-NaOH buffer (pH 9.5) at 50°C; it required Zn<sup>2+</sup> or Mn<sup>2+</sup> for enzyme activity. The half-life at 40°C and half denaturation temperature (T<sub>1/2</sub>) was 200 min and 45°C, respectively. Bioinformatic analyses along with biochemical properties confirmed that AfXDH belonged to the medium-chain dehydrogenase/reductase family. AfXDH exhibits higher thermostability and <italic>k</italic><sub><italic>cat</italic></sub> values than those of other XDHs. The feasibility of using AfXDH in <sc>l</sc>-xylulose production was demonstrated. AfXDH, when coupled with <italic>Streptococcus pyogenes</italic> NADH oxidase, efficiently converted xylitol to <sc>l</sc>-xylulose with 97% yield, suggesting its usefulness for the industrial <sc>l</sc>-xylulose production from xylitol.</p>