- SOC BIOSCIENCE BIOENGINEERING JAPAN
A xylanase gene (xynE) encoding XynE (110 kDa) was cloned from a 2, phage genomic library of Aeromonas caviae ME-1 which is a multiple-xylanase-producing bacterium. Upon nucleotide sequence analysis, we found that xynE comprises 2823 bp and encodes a protein of 941 amino acid residues (104,153 Da), which was similar to endo-beta-1,4-xylanases which are categorized to glycosyl hydrolase family 10. An Escherichia coli transformant that harbored pXED30 carrying xynE produced 110-, 84-, 72-, and 66-kDa xylanases in the cell-free extract, and 72- and 66-kDa xylanases in the culture supernatant. We purified the 66-kDa xylanase to electrophoretic homogeneity from a culture supernatant by a series of column chromatographies. The calculated molecular mass of the purified xylanase determined by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was 60,154.50 Da, and the xylanase was designated XynE,(60). Analysis of the N-terminal 10 amino acid residues and the determined molecular mass of XynE(60) revealed that XynE(60), is a product processed at the GlY(26)-Gly(27) and Thr(565)-Ala(566) sites of XynE by proteolytic cleavage. XynE(60) showed optimal activity at 55degreesC and pH 8.0, and was stable below 45degreesC and at pH 7.0-8.5. The K-m and V-max of XynE(60) were calculated to be 8.1 mg/ml and 6897 nkat/mg, respectively.
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- DOI : 10.1263/jbb.95.95
- ISSN : 1389-1723
- Web of Science ID : WOS:000181717100015