Chemoenzymatic preparation of 2-chloro-4-nitrophenyl beta-maltooligosaccharide glycosides using glycogen phosphorylase b

In the present work, we aimed to develop a new chemoenzymatic procedure for the synthesis of beta-maltooligosaccharide glycosides. The primer in the e nzymatic reaction was 2-chloro-4-nitrophenyl beta-maltoheptaoside (G(7)-CNP ), which was synthesised from beta-cyclodextrin (beta-CD) using a very conv enient chemical method [E. Farkas, L. Janossy, J. Harangi, L. Kandra, A. Li ptak, Carbohydr. Res., 303 (1997) 407-415]. Shorter chain length CNP-maltoo ligosaccharides in the range of dp 3-6 were prepared using rabbit skeletal muscle glycogen phosphorylase b (EC 2.4.1.1). Detailed enzymological invest igations revealed that the conversion of G(7)-CNP was highly dependent on t he conditions of phosphorolysis. A 100% conversion of G(7)-CNP was achieved during 10 min in 1 M phosphate buffer (pH 6.8) at 30 degrees C with the te tramer glycoside (77%) as the main product. Phosphorolysis at 10 degrees C for 10 min resulted in 89% conversion and G(4), G(5)-, and G(6)-CNP oligome rs were detected in the ratio of 39:26:34%, respectively. The reaction patt ern was investigated using an HPLC system. The preparative scale isolation of G(3-->6)-CNP glycosides was achieved by size-exclusion column chromatogr aphy (SEC) on Toyopearl HW-40 matrix. The productivity of the synthesis was improved by yields of up to 70-75%. (C) 1999 Elsevier Science Ltd. All rig hts reserved.