NUCLEOTIDE-SEQUENCE OF THE CLOSTRIDIUM-STERCORARIUM XYNB GENE ENCODING AN EXTREMELY THERMOSTABLE XYLANASE, AND CHARACTERIZATION OF THE TRANSLATED PRODUCT
M. Fukumura et al., NUCLEOTIDE-SEQUENCE OF THE CLOSTRIDIUM-STERCORARIUM XYNB GENE ENCODING AN EXTREMELY THERMOSTABLE XYLANASE, AND CHARACTERIZATION OF THE TRANSLATED PRODUCT, Bioscience, biotechnology, and biochemistry, 59(1), 1995, pp. 40-46
The nucleotides of the xynB gene of Clostridium stercovarium F-9 were
sequenced. The structural gene consists of an open reading frame of 11
61 bp encoding a xylanase (XynB) in family F of 387 amino acids with a
molecular weight of 44,377. The molecular weight of the enzyme purifi
ed from a recombinant Escherichia coli was around 41,000, smaller than
the predicted value, on SDS-polyacrylamide gel electrophoresis due to
the lack of 32 amino acids at the N-terminus. Intact XynB with a mole
cular weight of around 43,000 was immunologically detected in the tota
l cell proteins of a recombinant E. coli and C. stercorarium F-9. The
purified XynB was active toward xylan, carboxymethylcellulose, p-nitro
phenyl-beta-D-xylopyranoside and p-nitrophenyl-beta-D-cellobioside. Th
e pH optimum was 7.0 and it was quite stable over the pH range of 5 to
12 at 4 degrees C. This enzyme was optimally active at 80 degrees C a
nd retained about 50% of the original activity even after incubation a
t 100 degrees C for 10 min.