Characterization of kiwifruit xyloglucan.

Structural characteristics of xyloglucan are constant in the pericarp cell walls of kiwifruit (Actinidia deliciosa) throughout fruit enlargement and maturation. Most of the xyloglucan (XG) persists in the cell walls of ripe kiwifruit. XG from the pericarp tissues of 36-h ethylene-treated kiwifruit was extracted as hemicellulose II (HC-II) with 4.28 M KOH containing 0.02% NaBH(4), and purified using iodine precipitation and subsequent anion-exchange chromatography. This purifying protocol increased XG purity from 50 mol% in HC-II fraction to 62 mol% in the purified XG powder. The molar ratio of glucose: xylose: galactose: fucose in the purified XG was 10: 6.9: 2.1: 0.3. Gel permeation chromatography indicated that purified XG had an average molecular-mass of 161 KDa, a value that exceeds the 95 KDa M(r) determined for total polymeric sugars. Sugar linkage analysis confirmed the lack of fucose in the kiwifruit XG, but a small amount of arabinoxylan and low M(r) glucomannan remained associated with this fraction.