Unique transglycosylation potential of extracellular alpha-D-galactosidase from Talaromyces flavus

The transglycosylation potential of the extracellular alpha-D-galactosidase from the filamentous fungus Talaromyces flavus CCF 2686, chosen as the best enzyme from the screening, was investigated using a series of sterically hindered alcohols (primary, secondary and tertiary) as galactosyl acceptors. Nine alkyl alpha-D-galactopyranosides derived from the following alcohols - tert-butyl alcohol, 2-methyl-2-butyl alcohol, 2-methyl-1-propyl alcohol, 2,2,2-trifluoroethyl alcohol, 2-propyn-1-ol, n-pentyl alcohol, 3,5-dihydroxybenzyl alcohol, 1-phenylethyl alcohol and 1,4-dithio-dl-threitol - were prepared on a semi-preparative scale. This demonstrates a broad synthetic potential of the T. flavus alpha-D-galactosidase that has not been observed with another enzyme tested. Moreover, this enzyme exhibits good transglycosylation yields (6-34%). The enzymatic synthesis of tert-butyl alpha-D-galactopyranoside by transglycosylation was studied in detail.