Abstract
Pectin is one of the major cell wall polysaccharide found in dicotyledonous plants. We have investigated the properties of galactosyltransferase (GalT) participating in the synthesis of β-1,4-galactan side chains of pectin, and partially purified through several chromatographic procedures. Here, we report the chain elongation of galactan by a partially-purified GalT.
A crude enzyme was prepared from etiolated soybean hypocotyls. GalT was solubilized by treatment with a detergent and partially purified through ion-exchange chromatography. The chain elongation reaction was performed with 2-aminobenzamide (AB)-derivatized β-1,4-Gal7 as an acceptor substrate. The crude enzyme attached less than four Gal residues onto the acceptor, whereas the partially-purified enzyme transferred successively more than 25 Gal residues. Enzyme activity toward varying lengths of acceptor galactooligomers was examined. Activity increased with increasing degree of polymerization (DP) of the galactooligomers from 4 to 7, while the acceptors with DP 8-11 showed less acceptor efficiency than that of Gal7-AB.
