Enzymic alpha-galactosylation of a cyclic glucotetrasaccharide derived from alternan.
Alternanase catalyzes the hydrolysis of alternan, an alpha-(1-->3)-alpha-(1-->6)-D-glucan produced by Leuconostoc mesenteroides, resulting in the formation of a cyclic tetramer cyclo -->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->(2) (cGlc(4)). Two alpha-galactosidases, one from coffee bean and the other produced by a fungus, currently described as Thermomyces lanuginosus, were found to catalyze an efficient 6-O-alpha-D-galactopyranosylation of cGlc(4). The attachment of a nonreducing alpha-D-galactopyranosyl residue to the cGlc(4) molecule opens new possibilities for future applications of the cyclic tetramer, since the D-galactopyranosyl residue can be easily modified by D-galactose oxidase to introduce a reactive aldehyde group. The results also extend our knowledge about the synthetic potential of T. lanuginosus alpha-galactosidase.
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Institute of Chemistry, Slovak Academy of Sciences, 842 38, Bratislava, Slovak Republic.
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D002240:Carbohydrate Sequence; D003069:Coffee / Q000201:enzymology; D005658:Fungi / Q000201:enzymology; D005936:Glucans / Q000737:chemistry* / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D007934:Leuconostoc / Q000737:chemistry / Q000201:enzymology; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000378:metabolism*; D000519:alpha-Galactosidase / Q000378:metabolism*
D003069:Coffee; D005936:Glucans; D009844:Oligosaccharides; C439358:alternan; C439359:cyclic glucotetrasaccharide; D006026:Glycoside Hydrolases; C091143:alternanase; D000519:alpha-Galactosidase