Glycoside hydrolase involved in the hydrolysis of xylan, a major plant cell wall hemicellulose made up of 1,4-beta-linked D-xylopyranose residues. Catalyzes the endohydrolysis of the main-chain 1,4-beta-glycosidic bonds connecting the xylose subunits yielding various xylooligosaccharides and xylose (PubMed:1369024, Ref.5). The catalysis proceeds by a double-displacement reaction mechanism with a putative covalent glycosyl-enzyme intermediate, with retention of the anomeric configuration (PubMed:7988708). Produces xylobiose and xylose as the main degradation products (PubMed:19556747). Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. kcat is 68 sec(-1) with xylohexaose, 50.3 sec(-1) with xylopentaose, 0.162 sec(-1) with xylotetraose and 0.045 sec(-1) with xylotriose as substrate. Optimum pH is 4.5-5.5 (PubMed:1369024). Stable from pH 3.0 to 8.5 at room temperature and from pH 4.0 to 7.5 at 40 degrees Celsius (Ref.5). Glycan degradation; xylan degradation. Induced by D-xylose, dependent on the cellulase and xylanase regulator xyr1. Repressed by glucose through negative regulation by the crabon catabolite repressor cre1. Belongs to the glycosyl hydrolase 11 (cellulase G) family. In PubMed:1369024 Figure 2, this sequence is erroneously labeled xyn1, but in the remainder of the paper and all subsequent publications, this protein is referred to as xylanase 2 (xyn2).