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Thea-galactosidase from Aspergillus nidulans(AglC) belongs to a phyloge-netic cluster containing eukaryotica-galactosidases and a-galacto-oligosac-charide synthases of glycoside hydrolase family 36 (GH36). The recombinant AglC, produced in high yield (0.65 gÆL )1 culture) as His-tag fusion in Escherichia coli, catalysed efficient transglycosylation with a-(1fi6) regioselectivity from 40 mm4-nitrophenola-d-galactopyranoside | Aspergillus nidulans a-galactosidase of glycoside hydrolase family 36 catalyses the formation of a-galacto-oligosaccharides by transglycosylation Hiroyuki Nakai1 Martin J. Baumann1 Bent O. Petersen2 Yvonne Westphal3 Maher Abou Hachem1 Adiphol Dilokpimol1 Jens 0. Duus2 Henk A. Schols3 and Birte Svensson1 1 Enzyme and Protein Chemistry Department of Systems Biology TechnicalUniversity of Denmark Lyngby Denmark 2 Carlsberg Laboratory Valby Denmark 3 Laboratory of Food Chemistry Wageningen University The Netherlands Keywords acceptor specificity carbohydrate structural analysis transglycosylation a-galacto-oligosaccharides a-galactosidase Correspondence B. Svensson Enzyme and Protein Chemistry Department of Systems Biology TechnicalUniversity of Denmark Soltofts Plads Building 224 DK-2800 Kgs. Lyngby Denmark Fax 45 4588 6307 Tel 45 4525 2740 E-mail bis@bio.dtu.dk Received 17 May 2010 revised 2 July 2010 accepted 5 July 2010 doi 10.1111 j.1742-4658.2010.07763.x The a-galactosidase from Aspergillus nidulans AglC belongs to a phylogenetic cluster containing eukaryotic a-galactosidases and a-galacto-oligosac-charide synthases of glycoside hydrolase family 36 GH36 . The recombinant AglC produced in high yield 0.65 g L-1 culture as His-tag fusion in Escherichia coli catalysed efficient transglycosylation with a- 1 fi 6 regioselectivity from 40 mM 4-nitrophenol a-D-galactopyranoside melibiose or raffinose resulting in a 37-74 yield of 4-nitrophenol a-D-Galp- 1 fi 6 -D-Galp a-D-Galp- 1 fi 6 -a-D-Galp- 1 fi 6 -D-Glcp and a-D-Galp- 1 fi 6 -a-D-Galp- 1 fi 6 -D-Glcp- a1 fi b2 -D-Fruf stachyose respectively. Furthermore among 10 monosaccharide acceptor candidates 400 mM and the donor 4-nitrophenol a-D-galactopyranoside 40 mM a- 1 fi 6 linked galactodisaccharides were also obtained with galactose glucose and mannose in high yields of 39-58 . AglC did not transglycosylate monosaccharides without the 6-hydroxymethyl group i.e. xylose L-arabi-nose L-fucose and L-rhamnose or with axial
