PURIFICATION AND CHARACTERIZATION OF XYLANASE A FROM CLOSTRIDIUM-STERCORARIUM F9 AND A RECOMBINANT ESCHERICHIA-COLI

Xylanase A encoded by the Clostridium stercorarium F-9 xynA gene was p urified to homogeneity from a recombinant clone of Escherichia coli. T he N-terminal amino acid sequence and molecular weight (54,000) estima ted by SDS-PAGE of the purified enzyme were consistent with those dedu ced from the nucleotide sequence [Biosci. Biotech. Biochem., 57, 273-2 77 (1993)]. A xylanase was also purified to homogeneity from a culture supernatant of C. stercorarium F-9. Its N-terminal amino acid sequenc e, molecular weight, and enzymatic properties were quite in agreement with those of the recombinant enzyme, indicating that the xynA gene wa s predominantly expressed as a xylanase gene in C. stercorarium F-9. T he purified enzyme hydrolyzed xylotriose to yield xylobiose and xylose while it was less active toward xylobiose. It was optimally active at 75 degrees C and pH 7.0. K-m and V-max were estimated to be 1.9 mg/ml and 2.8 mu mol of xylose equivalent/min/mu g for oat spelt xylan, res pectively.