On the chain flexibility of arabinoxylans and other beta-(1-->4) polysaccharides.

The recent paper by Dervilly-Pinel and co-workers (Carbohydr. Res. 2001, 330, 365-372) presents a complete macromolecular characterisation of a series of de-esterified arabinoxylans extracted and fractionated from wheat flour. From their measurements, they were able to extract parameters related to chain flexibility, such as the Mark-Houwink exponent a and the chain persistence length. However, the estimate they obtain for the latter parameter is rather larger than would be expected, since the arabinoxylan backbone is beta-(1-->4) like cellulose and the galactomannans. By treating their data in an alternative, but well accepted manner, we are able to obtain a lower value of persistence length, which agrees well with estimates for this parameter for cellulose, in the literature, and our own recent measurements for a series of differently substituted galactomannans. These results suggest that the parameters obtained may be applicable to other beta-(1-->4) polysaccharides.