Galactomannan structure and β-mannanase and β-mannosidase activity in germinating legume seeds

Abstract

Structural changes in galactomannan on germination of lucerne, carob, honey locust, guar and soybean seeds, as measured by viscosity, elution volumes on gel filtration and ultra-centrifugation were slight consistent with a rapid and complete hydrolysis of a molecule once hydrolysis of the mannan chain starts. β-Mannanase activity increased and then decreased, paralleling galactomannan depletion. Multiple forms of β-mannanase were isolated and these were located in the endosperm. β-Mannanase had limited ability to hydrolyse galactomannans with high galactose contents. Seeds containing these galactomannans had very active α-galactosidases. β-Mannosidases were present in both endosperm and cotyledon-embryo and could be separated chromatographically. The level of activity was just sufficient to account for mannose production from manno-oligosaccharides.