Purification and Characterization of Two Xylanases and an Arabinofuranosidase from Aspergillus sojae

概要

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Two isoenzymes of xylanase (endo-1,4-β-xylanse, EC 3.2.1.8) and an arabinofuranosidase (α-_L-arabinofuranosidase, EC 3.2.1.55) were purified as electrophoretically homoheneous proteins from a solid-state culture of Aspergillus sojae. The molecular weights of the xylanases (X-I and X-II-B) and arabinofuranosidase (X-II-A) were estimated to be 32,700,35,500 and 34,300,respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Gel filtration chromatography gave molecular weight values similar to those obtained by SDS-Page for each of the purified enzymes. The isoelectric points of X-I and X-II-B were 3.50 and 3.75,and that of X-II-A was 3.90. The maximum velocities of arabinoxylan degradation by the xylanases were attained at 60℃ (X-I) and 50℃ (X-II-B), when the pH was maintained at 5.5. The xylanases were stable from pH 5.0 to 8.0,and up to 50℃ (X-I) and 35℃ (X-II-B). The optimum pH and temperatrue of X-II-A were 5.0 and 50℃, respectively, and it was stable from pH 5.0 to 9.0 and up to 50℃.The activity of these three enzymes was significantly inhibited by Mn^<2+> and EDTA, and stimulation by metal ions was not observed. Amino acid composition and sequence of the amino-terminus indicated that the xylanases of A. sojae were distinct from other know Aspergillus xylanses.
社団法人日本生物工学会の論文
1995-10-25