Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 28, 2003
Publication Date: N/A
Technical Abstract: Alternansucrase (EC 188.8.131.52) is a D-glucansucrase that synthesizes an alternating alpha-(1-3), (1-6)-linked D-glucan from sucrose. It also synthesizes oligosaccharides via D-glucopyranosyl transfer to various acceptor sugars. We have studied the acceptor products arising from methyl glycosides as model compounds in order to better understand the specificity of alternansucrase acceptor reactions. Methyl glycosides have the advantage of occurring in a single anomeric form and are easily purified using ion-exchange chromatography. The initial product arising from beta-methyl D-glucopyranoside was beta-methyl isomaltoside, which after subsequent D-glucosylation yielded beta-methyl isomaltotrioside and beta-methyl O-alpha-D-glucopyranosyl-(1-3)-O-alpha-D-glucopyranosyl-(1-6)-D-glucopyranoside. These products are analogous to those previously described from alpha-methyl D-glucopyranoside. The major initial acceptor product from alpha-methyl D-mannopyranoside was alpha-methyl O-alpha-D-glucopyranosyl-(1-6)-D-mannopyranoside. Alpha-methyl D-galactopyranoside yielded two initial products, alpha-methyl O-alpha-D-glucopyranosyl-(1-3)-D-galactopyranoside and alpha-methyl O-alpha-D-glucopyranosyl-(1-4)-D-galactopyranoside, in a 2.5:1 molar ratio. Beta-methyl D-galactopyranoside and beta-methyl D-mannopyranoside gave low yields of acceptor products, which were not isolated.