β-Glucan phosphorylases in carbohydrate synthesis

beta-Glucan phosphorylases are carbohydrate-active enzymes that catalyze the reversible degradation of beta-linked glucose polymers, with outstanding potential for the biocatalytic bottom-up synthesis of beta-glucans as major bioactive compounds. Their preference for sugar phosphates (rather than nucleotide sugars) as donor substrates further underlines their significance for the carbohydrate industry. Presently, they are classified in the glycoside hydrolase families 94, 149, and 161 (www.cazy.org). Since the discovery of beta-1,3-oligoglucan phosphorylase in 1963, several other specificities have been reported that differ in linkage type and/or degree of polymerization. Here, we present an overview of the progress that has been made in our understanding of beta-glucan and associated beta-glucobiose phosphorylases, with a special focus on their application in the synthesis of carbohydrates and related molecules