Background:
Lignocellulosic residues generated by various anthropogenic
activities can be a potential raw material for many commercial products such as biofuels,
organic acids and nutraceuticals including xylitol. Xylitol is a low-calorie nutritive sweetener
for diabetic patients. Microbial production of xylitol can be helpful in overcoming the
drawbacks of traditional chemical production process and lowring cost of production.
Objective:
Designing efficient production process needs the characterization of required
enzyme/s. Hence current work was focused on in-vitro and in-silico characterization of
xylose reductase from Emericella nidulans.
Methods:
Xylose reductase from one of the hyper-producer isolates, Emericella nidulans
Xlt-11 was used for in-vitro characterization. For in-silico characterization, XR sequence
(Accession No: Q5BGA7) was used.
Results:
Xylose reductase from various microorganisms has been studied but the quest for
better enzymes, their stability at higher temperature and pH still continues. Xylose reductase
from Emericella nidulans Xlt-11 was found NADH dependent and utilizes xylose as its sole
substrate for xylitol production. In comparison to whole cells, enzyme exhibited higher
enzyme activity at lower cofactor concentration and could tolerate higher substrate
concentration. Thermal deactivation profile showed that whole cell catalysts were more
stable than enzyme at higher temperature. In-silico analysis of XR sequence from Emericella
nidulans (Accession No: Q5BGA7) suggested that the structure was dominated by random
coiling. Enzyme sequences have conserved active site with net negative charge and PI value
in acidic pH range.
Conclusion:
Current investigation supported the enzyme’s specific application i.e.
bioconversion of xylose to xylitol due to its higher selectivity. In-silico analysis may provide
significant structural and physiological information for modifications and improved stability.
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