An acetylglucomannan esterase of Aspergillus oryzae; purification, characterization and role in the hydrolysis of O-acetyl-galactoglucomannan

• Published in: Journal of biotechnology Vol. 42; no. 3; pp. 197 - 206
• Main Authors: Tenkanen, Maija, Thornton, Jeff, Viikari, Liisa
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 16.10.1995; Amsterdam Elsevier; New York, NY
• Subjects: Acetyl esterase; alpha-galactosidase; Aspergillus oryzae; Aspergillus oryzae - enzymology; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Chromatography, Ion Exchange; Deacetylation; Electrophoresis, Polyacrylamide Gel; enzyme activity; esterases; Esterases - isolation & purification; Esterases - metabolism; Fundamental and applied biological sciences. Psychology; glucomannans; Hydrogen-Ion Concentration; Hydrolysis; industrial applications; Isoelectric Point; mannanose; Mission oriented research; Molecular Weight; O-Acetyl-galactoglucomannan; O-glycoside hydrolases; Physiology and metabolism; Polysaccharides, Bacterial - metabolism; pulp and paper industry; purification; Substrate Specificity; Synergism; Hydrolysis; Acetyl esterase; Aspergillus oryzae; O-Acetyl-galactoglucomannan; Deacetylation; Synergism; Purification; Enzyme; Environmental factor; Esterases; Fungi; Characterization; Enzymatic activity; Substrate specificity; Hydrolases; Fungi Imperfecti; Physicochemical properties; Thallophyta
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/0168-1656(95)00080-A

An acetyl glucomannan esterase (AGME) was purified to eiectrophoretic homogeneity from the culture supernatant of Aspergillus oryzae. This new enzyme had a molecular mass of 36 kDa and an isoelectric point of 4.6. It was most active in the pH range 5.0–5.5 and was stable for 24 h at 40 °C at pH 5.0–6.0. The purified esterase liberated acetic acid from O-acetyl-galactoglucomannan, O-acetyl-4- O-methylglucuronoxylan and α-naphtyl acetate. The specific activity was 10-times higher for acetylated mannan than for acetylated xylan. The enzyme was able to act on polymeric substrate but activity was clearly enhanced by addition of mannanase from Trichoderma reesei and α-galactosidase from guar seeds. Presence of mannanase also increased the liberation of acetic acid in long-term hydrolysis (24 h), while the addition of α-galactosidase had no effect. No significant synergism between these two glycanases and the previously characterized esterase of A. oryzae (FE), which is also able to deacetylate galactoglucomannan, was observed. Even though the AGME had 8-times higher specific galactomannan deacetylating activity than the FE, the maximum amount of acetic acid liberated from the polymeric galactoglucomannan by AGME was only 80% of that of FE. Both esterases clearly enhanced the action of mannanase and α-galactosidase in the degradation of O-acetyl-galactoglucomannan isolated from Norway spruce.