Efficient synthesis of a long carbohydrate chain alkyl glycoside catalysed by cyclodextrin glycosyltransferase (CGTase).

Alkyl glycosides with long carbohydrate groups are surfactants with attractive properties but they are very difficult to synthesize. Here, a method for extension of the carbohydrate group of commercially available dodecyl-beta-D-maltoside (DDM) is presented. (DDM) was converted to dodecyl-beta-D-maltooctaoside (DDMO) in a single step by using a CGTase as catalyst and alpha-cyclodextrin (alpha-CD) as glycosyl donor. The coupling reaction is under kinetic control and the maximum yield depends on the selectivity of the enzyme. The B. macerans CGTase favoured the coupling reaction while the Thermoanaerobacter enzyme also catalysed disproportionation reactions leading to a broader product range. A high ratio alpha-CD/DDM favoured a high yield of DDMO and yields up to 80 % were obtained using the B. macerans enzyme as catalyst. (c) 2009 Wiley Periodicals, Inc