Chemoenzymatic synthesis of 2-chloro-4-nitrophenyl beta-maltoheptaoside acceptor-products using glycogen phosphorylase b

III the present work, we aimed at developing a chemoenzymatic procedure for the synthesis of beta -maltooligosaccharide glycosides. The primer in the enzymatic reaction was 2-chloro-4-nitrophenyl beta -maltoheptaoside (G(7)-C NP), synthesised from P-cyclodextrin using a convenient chemical method. CN P-maltooligosaccharides of longer chain length, in the range of DP 8-11, we re obtained by a transglycosylation reaction using alpha -D-glucopyranosyl- phosphate (G-1-P) as a donor. Detailed enzymological studies revealed that the conversion of G(7)-CNP catalysed by rabbit skeletal muscle glycogen pho sphorylase b (EC 2.4.1.1) could be controlled by acarbose and was highly de pendent on the conditions of transglycosylation. More than 90% conversion o f G(7)-CNP was achieved through a 10:1 donor-acceptor ratio. Tranglycosylat ion at 37 degreesC for 30 min with 10 U enzyme resulted in G(8 --> 12)-CNP oligomers in the ratio of 22.8, 26.6, 23.2, 16.5, and 6.8%, respectively. T he reaction pattern was investigated using an HPLC system. The preparative scale isolation of G(8 --> 11)-CNP glycosides was achieved on a semiprepara tive HPLC column. The productivity of the synthesis was improved by yields up to 70-75%. The structures of the oligomers were confirmed by their chrom atographic behaviours and MALDI-TOF MS data. (C) 2001 Elsevier Science Ltd. All rights reserved.