AN APPROACH TO THE IDENTIFICATION OF A ß‐GLUCAN SOLUBILASE FROM BARLEY

Abstract

A ß‐glucan solubilase activity was demonstrated in barley extract. This enzyme catalyzed the dissolution of barley ß‐glucan by releasing a product having a narrow molecular weight distribution and a molecular weight of about 20,000. The enzyme was partially purified by ion exchange chromatography on DEAE‐cellulose and gel permeation chromatography on Bio‐Gel P‐100. Although carboxypeptidase activity was present in the crude extract of barley flour the partially purified ß‐glucan solubilase did not hydrolyse N‐CBZ‐Phe‐ala. Examination of extracts from different barley tissues indicated that the ß‐glucan solubilase activity was associated with the husks only; a large portion of the activity was extractable from whole barley kernels. About 85% of the enzyme activity in crude extracts from barley flour was retained after 40 min at 62°C. However, the enzyme was much more heat‐labile in extracts of whole barley kernels. The pH of maximal activity was found to be about pH 5.7 and results from column chromatography suggested that the enzyme had a low pl value and a MW between 5 × 104 and 6 × 104. 1988 The Institute of Brewing & Distilling