PHOSPHOROLYTIC SYNTHESIS OF CELLODEXTRINS

Transglucosylation reactions catalyzed by cellodextrin phosphorylase f rom Clostridium thermocellum were reinvestigated by using a series of cellobiosyl residues as glycosyl accepters and alpha-D-glucopyranosyl phosphate (Glc-1-P) as glycosyl donor. When cellobiose was used as an acceptor, various unsubstituted cellodextrins, ranging from water-solu ble products to crystalline precipitates were obtained, depending on t he concentration in acceptor. 4-Thiocellobiose, methyl beta-cellobiosi de, and methyl 4-thio-alpha-cellobioside could also be used as accepte rs with the same efficiency as cellobiose. The enzyme showed higher ac tivity when beta-cellobiosides bearing strong hydrophobic aglycons wer e used. A practical preparation of methyl beta-cellotrioside, cellotet raoside and cellopentaoside was achieved, using a 1:5 molar ratio of m ethyl beta-cellobioside to the glucosyl donor.