Phosphorolytic synthesis of cellodextrins

Transglucosylation reactions catalyzed by cellodextrin phosphorylase from Clostridium thermocellum were reinvestigated by using a series of cellobiosyl residues as glycosyl acceptors and α-d-glucopyranosyl phosphate (Glc-1-P) as glycosyl donor. When cellobiose was used as an acceptor, various unsubstituted cellodextrins, ranging from water-soluble products to crystalline precipitates were obtained, depending on the concentration in acceptor. 4-Thiocellobiose, methyl β-cellobioside, and methyl 4-thio-α-cellobioside could also be used as acceptors with the same efficiency as cellobiose. The enzyme showed higher activity when β-cellobiosides bearing strong hydrophobic aglycons were used. A practical preparation of methyl β-cellotrioside, cellotetraoside and cellopentaoside was achieved, using a 1:5 molar ratio of methyl β-cellobioside to the glucosyl donor.