CHARACTERIZATION OF KAPPA-CARRAGEENAN AND IOTA-CARRAGEENAN COILS AND HELICES BY MALLS GPC/

Iota- and kappa-carrageenans were degraded by ultrasonication to obtai n samples of different molecular weights. The coil and the helix confo rmations of the degraded and non-degraded samples were investigated by multi-angle laser light scattering (MALLS) coupled to gel permeation chromatography (GPC), and the weight-average molecular weight, M(w), a s well as the z-average radii of gyration, R(g,z), was obtained for al l samples in both conformations. The conformational state was controll ed by temperature and/or electrolyte content. All measurements were do ne under non-aggregating conditions, and an approximate doubling of th e weight-average molecular weight was seen for both iota- and kappa-ca rrageenan helices over the entire molecular weight range studied, impl ying a double-helix formation. Zimm plots for non-degraded kappa-carra geenan coils and helices confirmed the approximate doubling of the mol ecular weight for the helix conformation.