PURIFICATION AND CHARACTERIZATION OF AN ARABINOFURANOSIDASE FROM BACILLUS-POLYMYXA EXPRESSED IN BACILLUS-SUBTILIS

Two polypeptides showing alpha-L-arabinofuranosidase activity have bee n purified to homogeneity from culture supernatants of a Bacillus subt ilis clone harbouring the xynD gene [Gosalbes et al. (1991) J Bacterio l 173: 7705-7710] from Bacillus polymyxa. Both polypeptides, with dete rmined molecular masses of 64 kDa and 53 kDa, share the same sequence at their N termini, which also coincides with the sequence deduced for the mature protein from the previously determined sequence of nucleot ides (Gosalbes et al. 1991). The two polypeptides have been biochemica lly characterized. Arabinose is the unique product released from arabi nose-containing xylans which are substrates for both enzyme forms. Oth er natural arabinose-containing polysaccharides, such as arabinogalact ans, are not attacked by them but some artificial arabinose derivative s are good substrates for both polypeptides. Their arabinose-releasing activity on arabinoxylans facilitates the hydrolysis of the xylan bac kbone by some endoxylanases from Bacillus polymyxa.