xylosidase

Xylosidase refers to enzymes that catalyze the hydrolysis of xylose-containing glycosidic bonds, releasing xylose from xylooligosaccharides and from xylan, a major component of plant hemicellulose. The term most often denotes beta-D-xylosidase, which removes a single xylose residue from the non-reducing end of xylooligosaccharides or short xylan fragments. Some xylosidases also include alpha-xylosidases that cleave terminal alpha-xylosyl residues, reflecting substrate diversity in xylan-degrading systems.

Xylosidases are produced by a range of microorganisms, including bacteria and fungi, and are frequently secreted as part of coordinated plant cell wall-degrading enzymes. They play a key role in the breakdown of hemicellulose, acting in concert with endoxylanases that fragment the xylan backbone, thereby facilitating access to internal linkages and enhancing xylose production. In some organisms, xylosidases are involved in xylose metabolism and may be located intracellularly.

Biochemically, xylosidases belong to glycoside hydrolases, a diverse family of enzymes classified by sequence similarity and catalytic mechanism. They exhibit a range of pH and temperature optima and can be affected by product inhibition by xylose. The specific properties of xylosidases vary with their source and the exact substrate they act upon.

Industrially, xylosidases contribute to biomass conversion, pulp and paper processing, and the production of fermentable sugars from lignocellulosic materials. They are also used in research to study xylooligosaccharide metabolism and to optimize enzyme cocktails for efficient xylan degradation.