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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Renewable Product Technology Research » Research » Publications at this Location » Publication #216770

Title: Characterization of Alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS

item Cote, Gregory

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/16/2007
Publication Date: 10/16/2007
Citation: Ahlgren, J., Cote, G.L. 2007. Characterization of alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS [abstract]. 18th Annual International Light Scattering Colloquium. Abstract #13.

Interpretive Summary:

Technical Abstract: Native alternan is a high molar mass homopolymer of D-glucose produced by some strains of the bacterium Lueconostoc mesenteroides. It consists of glucose units that alternate their linkages between alpha-(1-6) and alpha-(1-3) between glucosyl units. The glucose units contained in the polysaccharide are derived from the hydrolysis of sucrose in a reaction catalyzed by the enzyme alternan sucrase. The native polymer can be produced in vivo by the intact bacterial culture or in vitro with cell-free supernatant containing alternan sucrase plus sucrose. The polysaccharide can be purified from cell-free supernatant by several rounds of alcohol precipitation. In this study we used the Wyatt Eclipse Field Flow Fractionation System to fractionate the polysaccharide and multi-angle light scattering (MALS) coupled with a refractive index detector to measure the molar mass and size of native alternan and compared these results to traditional SEC-MALS. The results show that native alternan was highly polydisperse, with a weight average molar mass of 50 million Da and an RMS radius of 45 nm. Conformation analysis showed the structure of the polysaccharide to be a random coil. The RMS radius measured by MALS was compared to the hydrodynamic radius (Rh) of the polysaccharide as measured by batch dynamic light scattering (DLS) using the Wyatt DynaPro detector; DLS analysis revealed an Rh of 52 nm that was stable from 25-85°C.