Purification of a new galactanase from Penicillium oxalicum catalysing the hydrolysis of β-(1→5)-galactofuran linkages

Abstract

An endo β-(1→5)-galactofuranase from Penicillium oxalicum has been purified 91-fold. The enzyme is a basic glycoprotein with a pI 7.9 and 20 % (w/w) carbohydrate content, galactose being the principal sugar. The apparent M(r) of the enzyme estimated by denaturing gel electrophoresis was 77000. The optimum pH was 5.0, and the enzyme was stable over the pH range 4.0-7.5. This enzyme hydrolyses specifically (1→5)-linked β-D-galactofuranose residues in homo- and heterogalactans, but did not hydrolyse o-nitrophenyl galactose and β-(1→5)-galactofuranbiose. K(m) and V(max) values were 1.2 mg.ml-1 and 0.55 μmol.h-1 respectively when Eupenicillium crustaceum β-(1→5)-galactofuran was used as substrate. The enzyme showed high affinity for different separation gels and proteins. The enzyme specificity and its mode of action showed that it could be an useful tool for analysing the fine structure of polysaccharides.