An alpha-L-arabinofuranosidase from Penicillium purpurogenum: production, purification and properties

Penicillium purpurogenum secretes arabinofuranosidase to the growth medium. Highest levels of enzyme (1.0 U ml(-1)) are obtained when L-arabitol is us ed as carbon source, while 0.85 and 0.7 U ml(-1) are produced with sugar be et pulp and oat spelts xylan, respectively. By means of a zymogram, three b ands with arabinofuranosidase activity have been detected in the supernatan t of a culture grown in oat spelts xylan. One of the enzymes was purified t o homogeneity from this supernatant using gel filtration (BioGel P-100), ca tion exchange chromatography (CM-Sephadex C-50), hydrophobic interaction ch romatography (phenyl agarose) and a second BioGel P-100 column. The enzyme is a monomer of 58 kDa with a pI of 6.5. Optimum pH is 4.0 and optimal temp erature 50 degrees C. The arabinofuranosidase is highly specific for alpha- L-arabinofuranosides and liberates arabinose from arabinoxylan. The enzyme shows hyperbolic kinetics towards p-nitrophenyl-alpha-L-arabinofuranoside w ith a K-M of 1.23 mM. A 36-residue N-terminal sequence is over 70% identica l to that of fungal arabinofuranosidases belonging to family 54 of the glyc osyl hydrolases. Based on the sequence similarity and other biochemical pro perties it is proposed that the purified enzyme from P. purpurogenum belong s to family 54. (C) 2000 Elsevier Science B.V. All rights reserved.