Studies on the Nature of Lignin - Carbohydrate Bonding

Abstract

Abstract A lignin - carbohydrate complex (LCC) fraction which was initially extracted with dimethyl sulfoxide from birch residual wood meal after stepwise MWL extraction (total yield 28%), contained about 7% qalacturonic acid together with about 4% glucuronic acid. Although galacturonic acid residue is well known to be a component of hardwood xylan, it also suggests the possibility of the existence of pectic substance in this LCC fraction. The nature of galacturonic acid in this LCC fraction was characterized by means of two purified pectinases, endo-polygalacturonase and endo-pectin lyase. It was concluded that most of the carbohydrate in this LCC fraction, especially xylan, is combined with lignin through pectic substance.