Levans. III. A light‐scattering study of <i>Streptococcus salivarius</i> levan in dimethyl sulfoxide

Abstract

Abstract A light‐scattering study of unfractionated and five fractions of Streptococcus salivarius levan was performed in dimethyl sulfoxide. The weight‐average molecular weights M̄ r in dimethyl sulfoxide, after adequate dissolution, agree with those obtained in water within a mean difference of 7%. The intrinsic viscosities [η] and root‐mean‐square z ‐average radii of gyration ( R g 2 ) z 1/2 are significantly higher in dimethyl sulfoxide than in water, reflecting the higher hydrodynamic volume in the former. The M̄ r , [η], and ( R g 2 ) z 1/2 of the fractions suggest that levan has a low polydispersity. The exponent of 0.12 of the Mark‐Houwink plot and model analysis confirm the branched and compact structure of levan.