Configurational statistics of polysaccharide chains. Part III. Linear β -(1 → 4') xylan and mannan

Abstract

The characteristic ratio C_N = 〈r²〉₀/Nl_v² of the β -D(1 → 4')-linked polysaccharides xylan and mannan has been computed as a function of the angle τ at the bridge oxygen atom and the degree of polymerization N. The calculated values of the characteristic ratio C_N are very high relative to their free rotational dimensions. The characteristic ratio of these polysaecharides converges to the asymptotic value at low degree of polymerization at higher τ values. The low values of the calculated characteristic ratio of xylan compared to cellulose and mannan for the same τ value indicate that the former is more flexible and assumes a compact configuration. A pronounced difference in the values of the characteristic ratio C_N of cellulose and mannan has also been observed lower τ angles (<120°). On the other hand, nearly the same values of C_N have been obtained at higher Τ angles (120°-125°), which suggests that, cellulose and mannan may have similar configuralons in certain solvents.