13C NMR studies of hyaluronan. 2. Dependence of conformational dynamics on chain length and solvent

Mary K. Cowman, Joan Feder-Davis, Daniel M. Hittner

Research output: Contribution to journalArticle

Abstract

The conformational dynamics of low molecular weight hyaluronan (HA) polymer and oligosaccharides have been assayed by 13C NMR T1 relaxation time measurements. For polymeric HA in aqueous solution, the average relaxation time for ring carbons was not significantly affected by changing the ionic strength or by changing counterion type. The average relaxation time of HA was found to be similar to that for chondroitin 4-sulfate or chondroitin 6-sulfate in aqueous solution. As has been observed previously for other polysaccharides, the segmental motions of HA chains studied at room temperature in aqueous solution appear to be dominated by viscous damping of the chain motions. Within a chain structure, there are variations in observed T1 that correspond to differences in relative mobility. The hydroxymethyl substituent group shows a difference in relaxation rate relative to the ring to which it is attached, depending on the ring configuration (glucose vs galactose). These differences correlate with relative rotational isomerization rates measured by ultrasonic relaxation. In short HA chains, the nonreducing and reducing terminal residues show much greater mobility than penultimate residues, and these are in turn more mobile than interior residues. In contrast, the more rigid hydrogen-bonded conformation of an HA tetrasaccharide in dimethyl sulfoxide solution shows less position-dependent variation in T1. These data are in accord with the dynamic nature of conformation-stabilizing hydrogen bonds for HA chains in aqueous solution.

Original languageEnglish (US)
Pages (from-to)110-115
Number of pages6
JournalMacromolecules
Volume34
Issue number1
DOIs
StatePublished - Jan 1 2001

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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