Cell Wall Metabolism in Ripening Fruit : III. Purification of an Endo-beta-1,4-xylanase that Degrades a Structural Polysaccharide of Pear Fruit Cell Walls.

A beta-1,4-xylanase has been purified from the mixture of carbohydrate-degrading enzymes found in a commercial preparation from cultures of Trichoderma viride. Purification from the desalted enzyme mixture is accomplished either by preparative isoelectric focusing or in two-column chromatographic steps. The xylanase has maximal activity at pH 5.0 and a molecular weight of approximately 13,000 daltons. The enzyme loses activity when heated to above 45 degrees C. The xylanase degrades xylans from larch and pear cell walls in an apparently endo-fashion.