Recent insights, applications and prospects of xylose reductase: a futuristic enzyme for xylitol production

Xylose reductase (XR) is an intermediate inducible enzyme of xylose metabolism responsible for the reduction of xylose into xylitol. It is an intracellular enzyme present in various facultative bacteria, yeasts, molds and algae in their cytoplasm. The active site of enzyme is polar in nature which is responsible for acid–base catalysis. The enzyme is folded into (β/α)₈ barrel and its substrate specificity is through C-terminal region. XR is an emerging industrially important food enzyme due to its major application in production of xylitol. Xylitol has shown remarkable applications in other industrial sectors such as food, biofuels, pharmaceutical, medical, odontological, textiles and cosmetics. This enzyme has been purified and characterized to understand its physico-chemical properties and stability. Further, robust microbial strains with tolerance towards high substrate concentration and toxic compounds are required to be developed for successful exploitation of XR at industrial level using agrowaste materials.