Enzymic Dissociation of Zea Shoot Cell Wall Polysaccharides : III. Purification and Partial Characterization of an Endo-(1 --> 4)-beta-d-Xylanase from a Bacillus subtilis Enzyme Preparation.

An endo-(1 --> 4)-beta-xylanase [(1 --> 4)-beta-d-xylan 4-xylanohydrolase, EC 3.2.1.8)] has been isolated from a commercial preparation of Bacillus subtilis alpha-amylase (Novo Ban 120). The purified xylanase exhibited an optimum activity at pH 5.5, and maximum activity at a temperature of 50 degrees C. The enzyme digests a (1 --> 4)-beta-d-xylan from larch yielding 4-linked xylobiose and xylotriose as predominant products but does not hydrolyze 4-linked xylotriose and xylobiose. The enzyme also digests a (1 --> 3), (1 --> 4)-beta-d-mixed linkage sequence xylan from Rhodymenia into 4-linked xylobiose and xlyotriose, and 3,4-mixed linked oligosaccharides having a degree of polymerization of four or more. It is concluded that this enzyme is capable of hydrolyzing sequences of four or more (1 --> 4)-beta-d-linked xylose residues.