Catalytic Properties and Partial Amino Acid Sequence of an Actinomycete Endo-(1→4)-β-D-Xylanase from Chainia Species

Abstract

<p>An endo-(l→4)-β-D-xylanase from a cellulase-free <em>Chainia</em> strain was substantially purified and subjected to amino acid sequencing. The first forty N-terminal amino acid residues show high homology with endo-xylanases from <em>Bacillus pumilus</em>, <em>B</em>. <em>subtilis</em>, <em>B</em>. <em>circulans</em>, and<em>Schizophylum commune</em>, less homology with endo-xylanases from <em>Aureobasidium</em> sp. and<em>Pseudomonas fluorescens</em>, and slight homology, but including a possible catalytic Asp residue, with catalytic domains of endo-xylanases from <em>Clostridium thermocellum</em>,<em>Cryptococcus albidus</em>, and an alkalophilic <em>Bacillus</em> and with a cellobiohydrolase from<em>Cellulomonas fimi</em>. The enzyme attacks substrates as small as xylotetraose and has xylosyltransferase activity. It is most active at pH 6 and 60°C and most stable between pHs 5 and 7.</p>