Fractionation of hemicelluloses from maize cell walls with increasing concentrations of alkali

Hemicelluloses were solubilized from depectinated walls of maize coleoptiles and leaves with increasing concentrations of alkali to yield three major fractions of polymers. A highly-substituted glucuronoarabinoxylan released by dilute alkali from walls of coleoptiles was present only in very small amounts in the walls of the leaves. The stepwise extractions with increasing concentrations of alkali resolved a relatively unbranched xylan from a mixture of mixed-linked glucan, xyloglucan and additional xylan from walls of young leaves. Delignification in acidic sodium chlorite solubilized a small amount of substituted xylan from walls of both coleoptiles and leaves, and rendered about one-half of the unextracted hemicellulose soluble in only 0.02 M potassium hydroxide solution. Delignification prevented the detection of highly-substituted xylans released by dilute alkali.