Xylanase (hemicellulase) activity in cell-free rumen fluid.

It has been shown that there is hemicellulase (xylanase) activity in cell-free filtrates of rumen liquor. This activity changes during the feeding cycle. The optimal pH and temperature for this activity have been found, as have the substrate-to-enzyme ratios. Many reagents, particularly heavy metal ions and phenols, inhibit the activity, but the activity is enhanced by reducing agents. No activity towards monosaccharides, disaccharides, or glycosides was found. The xylanase component was not stable, due to proteolytic enzymes in the rumen liquor, but could be purified by a variety of methods to give more-stable enzymes.