Substrate specificity of .ALPHA.-galactosidase from Mortierella vinacea.

Abstract

a-Galactosidase (melibiase, a-D-galactoside galactohydrolase, EC 3.2.1.22) from the mycelium of Mortierella vinacea1 ] catalyzes the hydrolysis of terminal a-galactosidic linkages of glycosides. The enzyme is used in the beet sugar industry for decomposing raffinose in beet molasses. For elucidating the substrate specificity of the enzyme, various kinds of a-galactose-containing oligosaccharides are necessary. However, the difficulty of substrate preparation has been an obstacle to the investigation. Vice versa, the enzymehas not been used for the structural analysis of 237 the oligosaccharides. This paper describes the specificity of the a-galactosidase from Mortierella vinacea toward several kinds of galactomanno-oligosaccharides since we were able to prepare the oligosaccharides.

Three α‐Galactosidase Genes of Trichoderma reesei Cloned by Expression in Yeast

“…Enzymes that can act on intact polymeric galactomannan have been isolated from seeds of Cyumopsis tetragonoloba (guar; Bulpin et al, 1990), Phaseolus vulgaris (French bean; Dhar et al, 1994) and Vigna rudiuta (mung bean; Dey, 1984) and from filamentous fungi such as Aspergillus tamarii (Civas et al, 1984b), Aspergillus niger (Adya and Elbein, 1977;Kaneko et al, 1991) and Trichoderma reesei (Zeilinger et al, 1993). Some cx-galactosidases have no activity on galactomannan such as the one described for Mortierella vinacea (Kaneko et al, 1990). Bacteroides ovutus produces two agalactosidases which do not act on intact galactomannan but are able to release u-galactoside units from oligosaccharides of the polymer, generated by an endo-I ,4-/?-mannanase treatment (Gherardini et al, 1985).…”

Carbohydrases

“…raffinose utilizer, also termed raffinase or melibiase, is used to hydrolyze raffinose to sucrose and galactose during beet sugar refining (Suzuki et al, 1969;Kobayashi and Suzuki, 1972;Kaneko et al, 1990). Raffinose interferes with the crystallization of sucrose obtained from molasses and a-galactosidase reduces the levels of this trisaccharide.…”

Demonstration of Activity ofα-Galactosidase Secreted byCucumis sativus L. Cells

“…Various naturally occurring or synthetic substrates may be used for these purposes [1][2][3]. α-Galactosidase (α-D-galactoside galactohydrolase EC 3.2.1.22) catalyzes the hydrolysis of the terminal non-reducing residues in α-D-galactosides.…”

“…The enzyme is used in the sugar beet industry for the hydrolysis of raffinose and stachyose. Microorganisms are the preferred sources of α-galactosidase [1]. Although α-galactosidase is generally present in plants, this source has not been used previously for the isolation of this enzyme [4].…”